I did my first few with a jig saw and a hacksaw.  Wasn't easy but it was all I had at the time.  Later I found a old bandsaw at a garage sale I thought I was in heaven.

I assume you're talking about using it to shape the limbs.  Use a fine tooth blade.  Most have jig saws have an adjustment that controls the oscillation of the blade; you'll want to have it set so the blade doesn't move forward to back as it goes up and down-just vertical movement.  That'll help keep the glass from splintering.  Should have good luck with that setup.

Use a heavy masking tape to cover the limbs and make your marks on the tape.  This will protect the FG from being scarred up by the foot of the jig saw and help keep splinters from turning in to tear outs.

Yeah use a metal blade, they are fine tooth.  wood blade would shred fiberglass.