In a Dynamic Spawn System (DSS) this raises a problem. High level players will never spawn low level creatures and thus can never gain basic skills to get more advanced ones. This is fixed by removing a skill requirement to skin a creature and instead basing the quality of skin attained on the skill level of the skinner. So a lvl 70 player with skill 1 skinning will only get poor quality hide and leather, but a lvl 70 player with 300 skill will get high quality leather. Not the quality of leather should be capped by the level of the mob, so a low level player skinning a low level mob will not get a very high level skin, instead he will get a low level skin.
This should also apply to mineral nodes. I like the node system that WOW uses, where minerals are available in certain areas, and are more populous in mines and rocky, mountainous areas. However, I don’t think they should be apparent what minerals they contain, instead that should be based off of the skill level of the miner, and also capped by the zone. So a high level miner in a high level area will get a really good and expensive mineral, but a low level miner in a high level area will get the same thing as if he was mining in a newbie area. Also a high level miner in the newbie area would probable get the low level ore, but there’s a better chance he would get a rare world drop off of those nodes (i.e. a special gem or some other material) that would be only mineable in the areas of that level. There should be a rare in every level bracket to encourage even high level miners to mine out those nodes, and thus also supply materials of all levels for crafting.
Skilling in these skills should be based on use. To get better at mining you have to mine, to get better at skinning you should have to skin, etc. However, I think that failing at a task should increase your skill slightly. Now this is not a point for point system like WOW, where every success gets you 1 more level in the skill, instead it should be based on skill xp, with a certain amount of xp needed for each level of skill, that is increasing (however, the skill gained from skinning mobs also increases as the quality of the product/mob skinned increases). So lvl 2 skinning might take 5 skill xp, and 3 might take 10, 4 will take 20. 5 would take 40, etc. It will become harder to skill as the skill increases, but it would be possible to skill all the way on just lvl 1 mobs…it would just take a few million times longer than skilling on higher level mobs. If you fail in skinning, you get some small amount of xp, and also you can try again, but the skin you will eventually get will be one quality level lower. So medium leather will become light leather, and light leather will become ruined scraps of leather. If you fail on a skin that would reward ruined scraps, the mob is unskinnable and despawns. Similarly if you fail on mining, the quality of the resource decreases (or the amounts) so instead of copper, you get copper dust, and if you fail again, you get no minerals and just rocks, and if you fail again, you get nothing. From a skill xp standpoint, it should be noted that the xp from a successful first skinning/mining attempt should be more than you can get by failing and then succeeding. So if getting a medium leather was worth 20xp, then failing once and getting light leather should be worth 12 xp (2 for failing and 10 for light leather) and failing twice and getting scraps should be worth 4 xp (2 for failing the first time, 1 for failing the second time, and 1 for ruined scraps).
This system does two things. First, it ensures that players can level their skills any way they want on any mob or node they want, but they will be rewarded for skilling as they level (they will have appropriate materials to sell for their level and will have the easiest skilling curve). I will make up a mock-up of a skill to demonstrate these ideas fully, but this is a pretty rough idea of what I mean by this skill system. It will make more sense when I make a full abstract of the skill system.