Andrew R Stewart 

I'll tack the lug points and other sides along the frame's centerlines. Two tacks per lug. I'll pin usually only once per lug to maintain alignment (tube rotational and length, not geometry) so during the many times I take apart and reassemble tubes/lugs on a jig before tacking everything lines up the same each time.

I do the main frame as one complete assembly and after tacking on the jig will align on a flat surface then complete the brazing free hand. Then another alignment check and back into the jig for the chain stays, tack, remove, align, complete braze and back into the jig for the seat stays. Between each brazing and reinstalling in the jig I do as much filing/sanding finish work because access is easier with less frame in a bench vice. I've begun to leave one seat stay/drop out un tacked or brazed and then use a builder's wheel for that last joint to insure best alignment.

Much the same with the fork. Tack, remove, check alignment and free hand braze. I do the steerer crown (as well as the BB/seat tube) as initial complete brazings before the rest of the steps.

Some day I plan to try all tubes in the shell and a hockey stick. I use to do the main frame in two pieces before I had a jig or flat surface.

Mike- Where are you? It would be cool to get together. Do you ever travel to bike/frame shows? Andy