The way I've done it is as follows: First cut a one- or two-layer piece of Kleenex-type tissue that approximates the size you'll need, with a bit extra allowed for the canvas to show some natural slack, rolls or folds. The mix up a solution of dilute white glue + tap water at around 1:1. I usually mix a few mL's of this on something like a plastic coffee can lid, or any other shallow basin. Then soak the tissue completely and lift out of solution, blotting away the drips. Place the wet tissue "in-situ" on the model where it will remain, and drape in the slack or folds. Allow to dry overnight. Paint when fully dry. Dry brush to add highlights or weathering effects. It usually doesn't need any more adhesive than the white glue, but if it does, superglue it to the model once the tissue is dry. Big point is, allow it to dry in the shape that you want it to be, on the model where it belongs. I've also used thin cut strips of masking tape to simulate the straps that keep bedrolls together, and I'll wrap the tape around the tissue "bedroll" while it's still wet. Pics to follow..