Step 1: What You'll Need
Thread (ideally one that has a nice contrast with the fabric).
Brown paper grocery bag (you can use any paper, but the grocery bag has some unique qualities that work better for this project.)
bottle to be wrapped.
Step 2: Making a pattern - step one
Align the bottom of the bottle at one edge, and mark the top (the point where you want the top of the bottle bag to be). You can make this longer than the bottle if you want.
Using one of the folds on the paper bag to guide you, draw a line from one end of the paper to the other. You can use a ruler, or you can use one of the folds from the paper bag as a guide to eyeball a reasonably straight line. (I drew my line using a fold as a guide.)