What are you trying to achieve from it? I would say just play with effects (thats how i learned) that and watching other engineers record... Everyone has there own way of using effects and song arrangement, thats what's ill about it... Double tracking is important, ad some little ad-libs and pan them slighty to one side...
This will add more fullness and make it sound nice... A sterieo Delay is good sometimes too for say a hook that is too spaced out... What that will do is stretch everything over a little and make it sound more active... But you have to play with that to get it right... I know with Logic (thats what i use) you always have to make sure your tempo is set right when adding a delay cause otherwise it can get thrown off beat and it will sound terrible...
Exciters, are nice when you want something to stand out.... Pitch shift is cool too i use that sometimes when playing around... Ace and Archetecht just put me up on a noise gate which is AWESOME! That effect is prbably one of the best to me if your recording without a booth or in a busy area... It will kinda cut anything thats not within the performers range out... But tweak that gently, too much is horrible...
What program or effects plug-in do you use?