A couple of bags I made lately. Basically, they are two pieces of fabric sewn together, pocket, if it has one, attached, handles sewn on, top hemmed, and bottom mitered. The black and mint one was made for a very little girl. The handle is braided fabric, an infallible way to make the color match. The other became my daughter in laws knitting bag.
I put the straps all the way down as this makes a much more durable product. You will notice when buying a purse that most handles or straps are attached at the top, and soon they pull out and there one is, shopping for another. If the strap follows the body of the bag down, it will probably last a lot longer.