Get some of that Colgate Whitening stuff thats like 4 or 5 bucks at Walmart, follow the instructions, and brush your teeth before using it, and (what I did) was brush mine about 5-10 minutes after using it as well, and I also use peroxide for mouthwash when I want to make a noticeable difference. The combination of all of that does a pretty good job.
As far as toothpaste goes, I don't think it really has much of an effect, but I use Crest whitening expressions cinnamin flavored toothpaste.. I just use it because I like the taste and aftertaste.