While looking over my wallet tutorial, I decided it was important to note that I have a tip for pressing really nice permanent crease. When I was making my daughter's kilt, I learned that the creases turned out better if I placed a heavy, flat metal object over the crease immediately after pressing. Using a weighted pot works fine. This way the material is held in place while cooling, making for a better crease. Also, the metal absorbs the heat which is good if you are impatient.
When making the wallet, another option to make sure the thing stays closed is to add hook and loop tape to the inside during the construction process. Since this was for my husband who hates Velcro in his wallets, I didn't add any.