A general rule of thumb is one nest for every four hens and a minimum nest size of 12" x 12" x 12" (if you have a top on the nest). A lot of the time they will only use one or two of the nests but "a lot of the time" dos not mean absolutely every time. I'd think four would be a good number for you.
Will full sized fowl hens lay in nests smaller than 12" x 12"? Yes, they will. But you need some guidelines and a 12 x 12 will suit any hen of any breed and is big enough that they can hatch eggs in if you let them when they go broody. Mine are 16" x 16" and they get used, they are not too big. If you make them this size three nests would probably be enough for your flock.
Sorry but I got a giggle out of "best". You see "best" used all over this forum but there is no such thing as best for all of us in much of anything. For practically anything there are a tremendous number of different methods/materials that can work extremely well. I'll include links to a couple of threads that show you what some people have done for nests.
Nest boxes
http://www.backyardchickens.com/t/41108/show-us-your-nest-boxes-ingenous-design-post-it-here/220
Nest Boxes
http://www.backyardchickens.com/t/4...-your-creative-nesting-boxes/80#post_12395882
People make nests out of buckets, milk crates, book cases, a chest of drawers, I've even seen a kitchen sink or bathroom commode used. Wood, plastic, or metal have been used. Some people modify something, others build from scratch. Some nests are pretty much enclosed while others are totally open on top. Some have entrances from the top, some from the side. Some are on the coop floor, some are elevated so you don't have to bend over to gather eggs. You are basically limited by your imagination and sometimes your sense of humor.
