I also have a top fin 10g. If you look in my sig you will see that I have a dwarf puffer in mine. I originally started with two puffers but they fought and one of them died within a few days
. If you want dwarf puffers then only get one. Great little fish! They won't eat flake food so you will need frozen food. I feed mine bloodworms. As for other fish, neons like to be in schools so you should get like 5-7. They will all be very happy in a 10g if you make sure the neons don't eat the food before the puffer gets some (puffers are slow eaters). Lots of plants is a good idea. Add a floating plant or two because puffers like to "sleep" at night. They really just hide in the plants all night and then come out when the lights come on.
One last thing. Be sure to cycle it. I strongly recommend fishless cycling. My 29g is almost done!
Good luck with the puffers!