The most common found at LFS's are usually Ghost Shrimp, Amano and or Bamboo Shrimp. Some also carry RCS, though buying through websites is usually cheaper. They are a great shrimp to have, but tend to breed like rabbits. With RCS you want to provide plants, DW and Rocks for the young to hide. Guppies will probably not bother adult RCS, but shrimplets are fair game as a snack.
I'd say start out with about 5-6 ghost shrimp and give them a month. Then you could consider either Amano or RCS ... all three are scavengers, though Amano and RCS also munch on Algae. Amano tend to be a bit bigger than RCS and will not breed in FW so that could be a plus. If you want the shrimp to breed, RCS's are the way to go. In a 10, you can start with 10-20 and let them multiply on their own.
With all three, your water must be pristine, Ammo, nitrites and even chlorine will kill them quickly. Keep temps in the 70's and your good to go.