Keep in mind the different places you'll be carrying your camera and how long you'll have it on your shoulder. If you will be carrying it while hiking, for example, you may want backpack style straps, which can also impact the overall design you choose for your camera bag. However, if you will only need the bag while carrying inside or to and from a particular location, a simple purse-like strap may serve your needs just fine.
Ultimately, the advantage of making your own camera bag lies in the many choices of design, material, straps, number of pockets and even size, and that you get to choose what works best for your photography style.