I want to start photography? - 2

What kind of camera ( Nikon ) Should I buy in the limit of 500$?
Any photography tips?

Nikon, Canon, many others are all good, just remember…

A camera is but a paint brush, it is more important who is holding the brush than which brush it is. All decent cameras can take wonderful pictures in the right hands. Spend your time studying great lighting and composition because even a great camera can't fix bad lighting or composition. And have fun with whichever brush you buy.

Well, there's only one nikon DSLR under $500 in the current lineup and that's the D3100 at $499, so there you go!
Tips: digital-photography-school.com has some wonderful tutorials.