As far as diapers go, I would recommend getting some wraps/covers, which would be put on after you fasten the basic prefold around the baby. They keep the prefold from soiling the clothing the baby is wearing.

I would also pick up a few pocket diapers/all-in-ones. I love those because they let you stick the prefold inside. It makes quick changes throughout the day and on the road great. And at night, the pocket diapers/all-in-ones have the added benefit of wicking away all of the moisture, so the baby won’t wind up sleeping in a wet diaper (well, he will, but he won’t feel it against his skin).

For wraps/covers, I used Litewraps. Inexpensive, basic, but quite functional and long lasting.
For the pocket diapers/all-in-ones, I swear by FuzziBunz and Happy Heiney’s. :)

Since newborns and infants pee and poop a lot, I’d recommend at least 2-3 dozen prefolds, and maybe 5-6 wraps? And at least 6-8 pockets/AIOs.