Looking at the code, the skills' information is as follows:
- Dabbling - No XP required - No bonus
- Novice - 100 XP required - 1.25% Bonus
- Adequate - 500 XP required - 2.5% Bonus
- Competent - 1200 XP required - 4.5% Bonus
- Skilled - 2500 XP required - 7.5% Bonus
- Proficient - 5000 XP required - 12.5% Bonus
- Master - 9000 XP required - 18.75% Bonus
Thus, a kitten who is splitting their time up between two jobs about evenly is going to still be under proficient when a kitten who'd focused on the same job all the time has made master. You're probably better off letting a small number of kittens focus on Farming continuously through the year; you won't get much benefit right away, but when they finally do make master, they'll be able to feed more kittens, especially with the upgrade later on that doubles how much bonus all skills give.
Even worse, any kitten who has skill in a job they're not currently doing, will slowly (very slowly) lose experience in that job. The effect of this is minor (five thousandths of an XP per second), but if you're idling for long stretches, it can stall progress if you're trying to teach a kitten two jobs.
In the end, though, it doesn't matter too much what you do this early in the game. Getting to master-level kittens takes a while, and swapping your kittens around won't stop them from making master in their jobs eventually; just slows it a little. Plus, once you get more Pastures, and the Hoe upgrades to your farmers, even a small handful of Dabbling farmers will be enough to feed a fairly large population through cold winters.
There are three main ways to get coal. The first two you'll get are the Coal Furnace and Deep Mining upgrades at the workshop. These will let you get small amounts of coal for each mine (0.003 per tick, 0.015 per second) and running smelter (base .005 per tick, .025 per second).
But, by far the best source of coal, is unlocking the Geology technology, and assigning Kittens to the Geologist job. Geologists are worth .015 coal per tick , equivalent to three smelters, or five mines. And kittens can improve at their jobs; a Master Geologist is earning about 0.026 coal per tick, which is over 0.1 coal per second each.
There are also quarries, which each give a +35% boost to mineral production, as well as another 0.015 coal per tick. They won't improve on their own the way Kittens improve their skills, but they still help a lot.
There are also several upgrades at the workshop related to coal which can help. Pyrolysis will increase coal gains by 20% from all sources. The Geodesy will increase Geologists' base coal per tick to 0.0225, making even a Dabbling Geologist worth four and a half Deep Mining mines. It also allows Geologists to produce a small amount of gold while they work.
Best Answer
Steel is an item crafted in the Workshop, requiring 100 Iron and 100 Coal for each craft. Like all other Workshop crafting items, it will appear in the crafting menu on the left side once you have any amount of it.