I made my tabard, seen here: http://www.cosplay.com/photo/2752836/
orig tabard ingame: http://images1.wikia.nocookie.net/__...Red_Tabard.jpg
It's basically clothe folded in half and sewn down under the arm on both sides. The fabric that lay on the portion of my lap was trimmed down to the width I needed.
Paint actually makes the tabard look more war-like and authentic, but that's my personal opinion. For my tabard I trace the symbol out on separate fabric and then glued it down to the front (you can also sew it down for sure), then I painted the symbol fabric with a nice brush of fabric paint since the glue does sometimes stain the fabric with blotches.
Been using it for two years now, extremely sturdy and looks decent.
SIDE NOTE: I would really avoid using the printer paper, it does crack and is hard to achieve a sharp look sometimes. As far as the bulging, tapering the sides has helped and wearing a sturdy belt about the hips is a plus. You will rarely lean over enough to make too much problems (in my experience I could barely even bend over anyway with the massive WoW shoulders) and if you do just pull the bottom of the tabard back down under the belt for a quick fix.