The best mods to start out with are the RS ones. . . (especially if your new to xmods and not sure bout after market upgrades)
The bearings is probably the best upgrade to start with
I think the stage 2 motor upgrade and AWD upgrade go hand in hand. I'd only recommend the stage 2 motor when you go with the AWD as well.
If you feel yourself being swayed into the darkside and into other mods, you may then want to look into some aftermarket upgrades like lithiums, aftermarket motor upgrades (which may require things like a electronics upgrade like FETTS) and so on. Just recommend doing some research before going into such aftermarket upgrades.