There is a member called Particle and he has a great video about forming the holster. You can find it at adamsleatherworks.com His video helped me out quite a bit, hopefully he doesn't mind me sharing his link. As for me I have found that having the holster at the correct saturation is important. Too wet and I get too many marks, too dry and its hard to form. Practice is key, I get better with each holster I make.
LOL Too funny! In the time it took me to type the above Particle replied to the post!