My suggestion:
For each skill (Blade/Archer/Magic/Summoner/Preist) you can level up when you gain enough experience. You gain experience by (attacking/shooting/casting/summoning/praying) successfully on an enemy/self. And, when you level up, your attack power/defense resistance/accuracy increase a little bit, and each skill can reach level 100. There should be milestones in these level ups, too. For example, reaching lvls 25, 50, 75 and 100 should get you a reward or something, like...the ability to attack/shoot in midjump, or to have a bonus of more frequent critical hits, or something. :|
And for tradeskills, it's the same way. Example: (tradeskills in bold)
Gathering fruits and herbs and flowers to make into a potion (alchemy) and then selling (bartering) it to a store to make some money.
Skills can reach level 100 and when you hit the 25, 50 and 75 levels, special rewards should be given to the player as a type of motivation.
Example: Level 25 in Mining: you can now mine ores faster than other players below level 25.
Level 50 in Mining: Any ores you gather from rock deposits can be sold for more money than they normally were worth.
Level 75: You can choose specifically what ores you wish to mine for in a rock deposits.
Level 100: You now gather 2x the amount of ores from a rock deposit.
