How do you like crafting your items? Do you want the "craft" ability to add more bonuses to the item (more fire damage, defense, life regeneration, critical attack, etc). OR do you want the craft to change the design of the item? Instead of short sword it becomes dagger, long sword, broad sword, etc? What other things could crafting to your items? Do you want only special crystals to be able to craft an item, or you must add another item of the same time? Tell me some good crafting practices/features.
This question is way too general. This is so game specific that any answer you get would not be at all worthwhile because it hasn't considered all the other important aspects. Some systems work really well in one game might suck in another with the exact same system.