If not absolutely necessary, never add lead.
1. Move the rudder and/or elevator servos to the rear.
2. Move the battery to the rear fuselage.

My method is to install the engine and throttle servos, then put the wing on and rubber band the servos and battery in various places until it balances. Usually I put the battery forward and the servos to the rear. This way I can move the battery to further move the CG back.