I used a diaper service for about a month when I first had my dd. Gift Certificates for the service were bought as shower gifts and it was nice to be able to cloth diaper but not have to worry about washing them the first month. If there is a service near you, I would highly recommend it. I decided to cloth diaper for various reasons, mainly the cost. This is why we are using prefold diapers and thirsties duo covers. One size diapers were way to small for my girl for the first 6 weeks of her life but the duo covers worked great. We rented covers for a few weeks from the service but weren't happy with them. I would highly suggest trying to find a store near you if you want to look at the products in person. Diaperswappers.com is also a great website if you don't mind buying used. I think we have 4 dozen prefolds (this is what my mom suggested) but could have easily got away with having less. You need to decide how often you want to wash them. They recommend every other day but I only wash twice a week.
Hope this helps!