Prepare your work surface by making sure walls or floors are clean and free of dust, furniture is accessible from all angles, drawers are removed and all handles or other interfering hardware is taken off. Use masking tape to block off areas that you don't want covered with leather treatment. If the surface has a glossy or finished topcoat, you will need to lightly sand it and wipe it down with a damp, lint-free cloth.
Prepare your materials by tearing the paper bags into roughly 1 foot by 1 foot squares. Don't worry if the edges are uneven, if the squares aren't quite the same size or if you get scraps that don't look anything like squares. For greater effect, wad the pieces up into tight balls and then carefully open them out flat again. Stack them with any lettering or other print on the same side (top or bottom) so you won't accidentally advertise your favorite grocery store in your finished design. Pour the glue into the paint pan.
Apply texture to your work surface by spreading glue onto the printed side of the brown paper pieces with a lint-free cloth or paint brush and affixing them to the surface like wallpaper. Start from the center and spread out toward the edges, overlapping pieces as necessary. Use a box cutter to cut away excess paper at the edges, or use the blunt edge to press paper into tight creases. Once the surface is covered, brush an extra layer of glue over the whole thing. Allow the glue to dry according to the recommendations on the bottle.
Mix one part acrylic paint with one part glaze medium for each of the shades you've selected. Similar but different tones will create a more realistic effect. Use cloths, sponges or paint brushes to stipple color onto your dried surface, allowing the colors to intermix or stand alone as you work. You may need to apply two coats for optimum effect. Once you have the look you want and the final coat is dry, apply a coat or two of polyurethane clear coat to keep the surface protected and easy to clean.