An easy way to figure out a good size for the bag is to check out the boxes in your kitchen. Maybe a large cereal box? Measure the front and include half the sides and bottom, add a seam allowance and there you go! Make an outside and a lining, square the bottom corners, add straps and you are done. Also, if you want more of a messenger bag, simply add a flap and attach to top before you attach lining. If you google tote bags, there are many free patterns available.