im new to flying and i was just wondering if there is any good tips on how to find the c of g on a plane without the use of a proper gauge?
at the moment i mark the c ogf g point on the plane and use my middle fingers to pick it up, this however is hard to do and probabaly totally inaccurate.
i have heard that you can tell if its nose heavy or tail heavy by doing a spin and if it spins rapidly that means its nose heavy is this true?
also some planes you must invert to get the c of g why is this?
and should it be done with a full tank or half ect..?

any help welcome thanks