I know that the developers have stated that they don`t want to have leveled skill increases. I think I understand why, and if so, I agree with them completely. The sort of silliness that comes from reaching level 100 swordmaking or whathaveyou in most games is pretty unappealing to me.
That said, there already are levelled skills -- the combat skills. And because the tech tree is fairly small, this pushes everyone to eventually gear up into powerful warrior sooner or later. I think its really important to let bakers miners and TANNERS also improve. (BTW why don`t we get any xp for tanning hides? we get it for picking APPLES, fer chrissakes.)
So, that said, here is my minor suggestion. I`m going to do my best to make a chart that is legible, but bear with me.
Have all the skills level. Levelling a skill does NOT grant any extra ability. As a matter of fact, the higher you increase your skill, the more it costs to further increase the skill, and the LESS you gain from it. Not more, LESS.
Take a look at sample skill progression chart: (maybe for basket weaving)
lvl rnge (approx) Stm cost Fail rate Break rate (on fail) Other
1-3 150% 75% 50%
4-8 120% 50% 25%
9-15 100% 25% 10% - unlock next skill in progression
16-20 100% 10% 5%
This would probably be the point where most people would say "enough is enough!" and move on to another skill. But for those who wish to continue mastering the skill, each progressively expensive upgrade would result in a smaller and smaller benefit. 1% knocked off here or there each level, or something like that. But you COULD do it if you wanted to be the best miner/baker/tanner there were.
Another advantage to this is that it allows relatively painless early game spamming. People at a low level are going to fail a LOT, and break a lot of branches or mangle a LOT of clay. Fails will still give xp, same as success. this will result in much less "litter" from spamming. On the other hand, the high stamina cost of beginners doing this will prevent it from simply becoming a click-fest forever.
Yet another advantage is that it will promote apprentice ship, and low level characters cooperating with high level characters. For example, if the agriculture skill has low level characters harvesting 2 seeds per plant, and high level ones harvesting 4, the high level characters will essentially ban the low level ones from practicing on their fields -- it costs them food. If, on the other hand, the RESULT is the same but the amount of effort put forth to ACHIEVE the result is what skill changes, then you will simply see the experienced characters laughing at the new guys who are exhausted after only planting half a row.
Also, new forge workers would be doing tasks with the cheapest available material -- if they screw up with a piece of pig iron and break it, no problem, but screw up with a bit of mithril and destroy it and...well, you get the picture.
Last point, most characters will not use this level up system past 10 or so....the results diminish, it becomes more expensive, and they can move on to the next step in the tech tree already. But some people WILL keep going, and that means you will have a population where there are a few newbies, a wide number of people who are competent, and a very, very few masters. Which is a pretty good model of the real world, innit?
Let me know what you think. Ive tried to avoid any radical or innovative ideas in the post.