Neon tetras are good. Glowlight tetra are good too. Platies can work as well. Harliquen Rasboras are okay with a betta, but they are timid fish and can somewhat be stressed with a betta.
I've heard mixed things about danios, cherry barbs, and larger tetras. Sometimes they work, but lots of times these fish will fin nip a betta.
Bottom feeders like cories are good in a betta community tank too. Also otos are good and will keep your algae in check.
Avoid fish that are larger than a betta, fast swimmers (like barbs), and anything with long flowing fins (like guppies)
Hope this helps. Have a back up plan just in case. It's hard to predict how a betta will react to tankmates. I took my "very calm" betta, and put him in with my glowlight tetras. The tetras were great, the betta freaked out and chased all the other fish away. (Which my tetras seemed to think was extra fun, all they did was taunt him after that. . .) So it's hard to tell. Good luck!