check out worlds greatest magic. they have a finger ring magic dvd with lots of cool routines and tricks. very good place.
also ring leader is also very good place to start. he goes thru EVERYTHING. its a great routine too.
Also try the Tarbell Course, all of them expect Vol.4, I think, has material on ring magic. (It's old but it's really great stuff) and also from experience I can tell you that Richard Sanders's Any Ring handkerchief is very worthy of your attention.