Well, I suppose with RE6 it's a love hate thing. Some shooter fans had fun, but most RE fans were pretty upset.... bringing down the metacritic score to 5/10. Set low low expectations if you actually like RE games.
To stop being a dick and try to answer your question tho... IGN has a decent walkthrough up:
http://www.ign.com/wikis/resident-evil-6
Some of the advise in the walkthrough is iffy, but comments are enabled so you'll see people discussing things, like, that they think the defense skill is quite useful.