I believe the best way to advance in an area is the way an old DOS game, Eye of the Beholder, handled it. You did it, so you got better at it...period.
Using this method, no matter what you wanted to do, you would advance by doing just that. Instead, players are forced to go kill to be able to train in mining, metallurgy, crafting, etc.
As far as stats, whatever activity you partake in would determine which stats advance. Use crystal way, gain charisma...fight a MOB, gain in STR, AGI, and END...run long distance, gain END, etc. The more focused an activity is on a stat, the quicker it would improve.
If this could be implemented, it would create a completely RP environment.
