Mike L
I use silicone caulk when I paint walls. I tape the trim and leave about a 1/16th gap. I use the caulk to seal the gap and allow the tape to come off easy.

When I replace glass I do about the same thing. I tape the face of the glass leaving a small gap between the sash and the face of the glass. I then apply a small bead in the corner of the sash and insert the glass. If any bleeds out the tape stops it from getting all over the place. Keep a damp rag handy to wipe up any squeeze out.