I pick the plane up by the spinner, with the engine away fro the compression stroke, so it will rotate freely, then pick it up by tail, as near to the centerline of the fuse as I can. If I can't get the plane to hang in equilibrium from this point, I go a little higher with the aft pick-up point. Maybe up the rudder. When I get to a place were the plane will hang in equilibrium, then if one wing is down, I add weight to the opposite wing tip. If it looks like it will be a minor amount of weight, I use small nails or brads taped to the wing tip. I keep adding until I achieve a balance. If it is a substantial amount, I may cut open a wing bay so I can glue in some lead sinkers.