Balance low wing planes upside down. Balance high wing and mid wing planes right side up. I like to balance my warbirds slightly nose heavy as they fly better that way. Like many have said "numerous" times before, it's better to balance a plane slightly nose heavy than tail heavy.

The CG for your plane can be found in the instruction manual that came with the plane. If you no longer have the manual, then try to get the CG info from the manufacturer website.