Theres a couple of places u can look. Try the PKR school. on pkr.com. It isnt too bad, little bit of strategy on there I would have thought.
For lots of decent articles, written in a realitively easy going and slightly entertaining way look at
Top Online Poker Sites: Free Software, Strategies & Poker Site Reviews
I used to read that site a lot.
Both games are profitable, as different people have different opinions. The thing about NL is that you need to be prepared for complete randomness in peoples plays.