That's a pretty involved question. Do you want the cheapest type or the easiest type?
Really, it's not nearly as complicated as it sounds. There are a few basic types, and everything else is just the bells-n-whistles. The cheapest way to use cloth is to do the old fold-n-pin method with plastic pants like previous generations did. The easy way is with pockets or AIOs. They're just like disposables except that they have snaps or velcro. Others can give you a much better explaination than I can. There are much more modern (and comfortable!) variations of the plastic pants type and things like that.
I'm using FuzziBunz pockets. It's the only thing I ever tried and they work well, so I didn't bother to check anything else out.

How many you need depends on how often you plan to wash. Newborns go through about twice as many diapers than older babies do, so you'll need more of those. I can't speak for all brands, but for me, FuzziBunz seems to line up with Pampers like this: Small = 0-1, Medium = 2-3, Large = 4-5. I bought 15 mediums and 15 larges when I was pg. Ben's huge for his age, so he was wearing mediums by 2 months and larges by 7 months. What sizes go with what ages really varies as much as babies themselves do!
Good luck in your search!

I hope that helped just a little.