Skills in Stardew Valley offer you some character customization options, and leveling them unlocks new items you can craft. Many are highly useful for money-making and utility. This guide highlights some of the most important unlocks for each of the game's 5 skills and will lead you to more information on each of them.

List of Skills and Useful Crafting Unlockables

Stardew Valley features 5 skills, each with 10 levels and 4 separate professions that can be chosen to give your character a boost. Each of the skills will unlock new crafting and cooking recipes as you level, expanding your options on the farm and increasing your farmer's ability to earn money and accomplish your goals. This list of skills and unlocks leads to more in-depth skill guides that can teach you the fundamentals of each of them.
Leveling Skills
You'll level skills as you use them, with each level up taking substantially more work. While I'll touch on how you level each of the skills in Stardew Valley, I have a guide dedicated to Skill XP and how to level them which may have a bit more info on the mechanics. The skill guides also cover this aspect and list all of the crafting unlockables for that skill as well as how to make use of it.

Skills

Combat Skill

Stardew Valley's Combat skill gains experience as you slay monsters in the mines, skull cavern, secret woods, and any area with enemies. You can't begin to use this skill until after day 5, when the way to the mines is cleared. Each level gives you +5 additional hp, though weapons take no energy and thus proficiency is a non-issue. As you descend the mines - where you use Combat most - you will level it, and also unlock new weapons the deeper you travel. Combat in Stardew is fairly simple, but you can augment your character with up to 2 rings and one pair of boots, found on the inventory screen. Learning the rhythm of combat is important for harder enemies, but for the most part you'll spam attacks and try to position enemies to take advantage of knockback/stun while fighting. An enemy with their back to the wall is especially vulnerable!
Notable Crafting Unlocks for Combat:
  • Sturdy Ring (level 1) - Craft the sturdy ring to cut the duration of negative status ailments in half. Useful against a few types of debuffs you'll encounter in the mines. A nice ring if you're not so hot at combat. Many people will use magnet rings to gather far-away items.
  • Life Elixir (level 2) - Fully heals your character. Not that great but it's also able to recover 200 energy. Takes 1 each of the four mushrooms, easily obtained in quantity (over time) if you chose mushrooms over bats for the cave.
  • Warrior Ring (level 4) - Gives you a burst of speed sometimes when an enemy is slain. Good for getting back on track after a fight, since the clock is always ticking while you're in the mines or Skull Cavern.
  • Slime Egg-Press and Slime Incubator (level 6 and 8) - These two items go with the Slime Hutch to let you breed slimes (which you can fight). They can be useful for collecting slime as well as the drops from the harder (purple/black) slimes. Having one on your farm may lead to a rare event that can let you farm your slimes for other drops in the form of a few rare minerals.
  • Ring of Yoba (level 7) - This ring gives you a chance to have extended invincibility when damaged, allowing you to have time to get out of sticky situations when surrounded and avoid a little more damage. It can be a real life-saver. Works best when your luck is high that day.
  • Iridium Band (level 9) - The Iridium Band is the ultimate ring in Stardew Valley, offering magnetism, +10% damage, and a glowing effect. What is more, two can stack. Though you may want to use a ring of Yoba, two Iridium bands is probably the ultimate combo as the magnetism is highly useful when you're detonating mega-bombs in the Skull Cavern.

Farming Skill

The Farming skill will rise as you harvest crops. No other activity gives skill experience. Leveling farming will give you some nice craftables that let you expand on your ability to make money with produce, from the cheese press to kegs and other items. Farming skill gains give you hoe and watering can proficiency, which makes those two activities consume less energy. Look at the farming guide to learn more about making money with this skill. Check out the linked guides below for in-depth information on some money-making aspects of farming as well as bundle completion..
Notable Crafting Unlocks for Farming:
  • Scarecrow (level 1) - Scarecrows are essential to keeping crows from eating your crops. They protect an 8-tile radius, so one can work wonders for a medium-large sized garden. You can move them at any time using the pickaxe.
  • Fertilizer (level 1 ) - Fertilizer gives a chance at better quality plants. Use it after tilling the soil but before planting. Thankfully, it takes only sap to craft, so you can get a large quantity just chopping down some trees.
  • Mayonnaise Machine (level 2) - The mayonnaise machine lets you make more money from eggs that chickens provide, many players' first experience with managing livestock. It's not wildly profitable but does help you to get more out of that investment.
  • Bee House (level 3) - The bee house lets you generate income from a single flower, with more expensive flowers making more money. The bees will passively produce honey so long as there is a flower in range, so you've only got to ensure the life of that flower and collect the honey when it is ready!
  • Preserves Jar (level 4) - The preserves jar lets you make pickles from vegetables and jam from fruits. A very handy item for the mid-game.
  • Cheese Press (level 6) - Cheese presses turn Cow and goat milk into two types of cheeses, with the latter more valuable. Cheese is also a decent healing item, though you may be better off selling it and buying salads if that's your intention.
  • Oil Maker (level 8) - Oil makers can generate gobs of cash if you've got pigs on your farm. You can produce truffle oil, certainly one of the most profitable Artisan Goods in the game.
  • Keg (level 8) - Like the oil maker, you can make a lot of money via hops/wheat for beer and pale ale, or using fruits to make expensive wines. The final value of wines is based on the base price of the fruit - try it out with ancient seeds for some serious cash.
  • Seed Maker (level 9) - The seed maker can allow you to make foraged produce for any of the four seasons if you put in the right vegetable. See this tutorial for in-depth information.
  • Iridium Sprinkler (level 9) - While you unlock several other types of sprinkler along the way, the Iridium sprinkler covers a large area and is the first to be efficient material-wise for making a massive farm.
For More info on Farming See:
Crops to Grow for Bundles (By Season)
Spring Crop Prices
Summer Crop Prices
Fall Crop Prices
Winter and the Seed Maker for growing winter foraged produce.

Fishing Skill

This skill is leveled by successfully catching fish or collecting them from crab pots. Fishing is the skill that Stardew Valley players have the hardest time figuring out how to use. The mini-game is a little challenging at first, but with some practice you'll easily reel in all but the most difficult fish. I have separate guides on How to catch fish and how to use bait and tackle for when you level the skill a bit. See the main fishing guide for some extra fishing spots. There are also pages on the fish found in the four seasons and where to catch them!
Notable Crafting Unlocks for Fishing:
  • Bait (level 2) - See the guide above for how to use bait. Bait decreases the time for fish to bite.
  • Crab Pot (level 3) - Crab pots can be placed in water and will give you items each day. Good for getting garbage for the next item, but you'll also catch things like lobster which can be valuable.
  • Recycling Machine (level 4) - You'll catch glasses, newspaper, cds, trash and driftwood when fishing. Put them in the recycling machine and get valuable and useful crafting items out of it, as opposed to selling that trash for only 2-3G each. It's a very good way to help yourself with crafting materials that are not as easy to come by early on in the game.
  • Better Bait and Tackle (level 6) - At level 6, you can start using the best fishing rod in the game, and it's capable of taking tackle. These have a variety of effects, outlined in the guides above. In short, tackle can make fishing much much easier. The normal fish become effortless and hard fish are simpler to catch. Combined with fishing levels, only legendary fish should give you trouble.
  • Worm Bin (level 8) - The Worm Bin will automatically generate worms for your fishing endeavors (in the form of normal bait). Though bait isn't expensive, it's nice to have these if you fish regularly.
For More Info on Fishing See:
Catching Fish in Spring
Catching Fish in Summer
Catching Fish in Fall
Catching Fish in Winter

Foraging Skill

The foraging skill is leveled by collecting wild plants and chopping down trees. This skill gives some unique unlocks that help you collect a couple of rare resources that can only be gained from nature. Gaining skill in it and upgrading your axe will make woodcutting much less strenuous on your character. You'll need a lot of wood, so it's not an awful idea to plant some trees.
Notable Crafting Unlocks for Foraging:
  • Field Snack (level 1 ) - This is a cheap, craftable snack made of the three types of tree seeds. It gives 45 health and energy and can be found in the crafting tab. Good if you do not yet have a kitchen. You should save some of your seeds for planting trees, however.
  • Wild Seeds (levels 1, 4, 6, and 7) - You'll unlock spring, summer, fall, and winter wild seed recipes as you level. These can be handy for when you want to grow more of the harvested items, or if a villager happens to like them for a gift.
  • Tapper (level 3) - Placing tappers on trees lets you get one of three kinds of resource (maple syrup, pine tar, oak resin) which are used in crafting/cooking recipes. The items themselves are valuable enough that you could make a farm dedicated to growing these things, though nothing will top pigs/oil maker or simply farming. Just another fun idea!
  • Charcoal Kiln (level 4) - A good item if you have not had much luck with coal in the mines. You can turn 10 wood into one piece of coal with the charcoal kiln.
  • Lightning Rod (level 6) - This one is used during summer thunderstorms to make battery packs, one of the more rare items in Stardew Valley. They're used in advanced crafting, so you'll want to make some of these to harvest nature's power. Each lightning rod can store one charge for 24 hours, and prevents the bolt from striking something more valuable as well!
  • Totems (levels 6, 7, 8, 9) - You can make single-use totems to instantly warp to one of three places (Which are not covered by the mine cart). The Rain totem is handy if you need to catch a specific fish that only comes during rain, and of course waters your crops. You have a greater chance of rain the next day when you use this. Warp Totem: Farm is good for getting out of bad situations in the skull cavern or for when you're out late and want to go home instantly. Mainly for the end-game.

Mining Skill

The mining skill is (nearly) essential to leveling up your tools and crafting things for your farm that require metal. Particularly Iridium Sprinklers from the Skull Cavern. You'll one day want copper/steel/gold variants and this is the cheapest route. You'll level combat simultaneously as you work your way through the mines. Skill experience is gained by breaking rocks in any way (even with bombs), and levels come with proficiency in addition to unlocks. Upgrading your pickaxe will make harder rocks take far less hits and thus consume less time and energy.
Notable Crafting Unlocks for Mining:
  • Furnace (level 0) - You'll get this recipe from Clint the blacksmith after you've been to the mines and located ore. Find the furnace on your crafting tab under the esc menu. Having coal and ore in your inventory (5 ore each) you can smelt ore into bars.
  • Bombs (levels 1, 6, and 8) - Bombs let you blow up large areas, with larger variants unlocking with more levels. They're a little pricey to craft but are a worthy use of materials when you're trying to make it as deep as possible in the Skull Cavern.
  • Transmutations (levels 4 and 7) - Level 4 lets you transmute copper bars into iron and level 7 iron into gold. Head to your crafting tab to use it, not the furnace!
  • Crystalarium (level 9) - Place a gem into the Crystalarium, and it's locked in. The Crystalarium will then dispense that gem at regular intervals. One diamond becomes 10 over time if you are patient, and diamonds are the most profitable and rare item to place inside. More Crystalariums can produce a variety (or more of one kind) for you and help as gift-giving options to make friends with the villagers in Pelican Town.