Just to add my two cents here. I'm a new member as well and I've found it easier to use paper mock ups first of any idea I have. I look at something and try to get some what of a basic dimension of what I want. I draw everything out on paper to get all the details like zipper position, stitching lines, folds and pockets etc.. I then figure what leather will work best for what the project calls for.
I bought a huge roll of contractors paper from home depot (about 8-12 bucks depending on paper weight) and it's been my best friend. I use clips or mini clothes pins to hold my mock ups together.
If you want you can message me and I can show you a few examples of how I do my templates from drawings.