Leveling up those trees would be calculated on moving to higher teirs of ingredient requirements. For example:
Leveling smithing up to steel teir would require practice with basic iron, then leveling to Dwarven/elven teir would require more experience with steel smithing, and etc and starting each teir, daggers would be easier to smith than a full two-handed blade or body armor.
As you go up, harder ingredients would easier to acquire as your character levels up, and has access to better dungeon loot.
The same principles could apply for Alchemy and Enchanting.
What does everyone think? Thoughts? Agree or disagree?
EDIT: iPhone auto correct fail.
