Just a quick suggestion; Go to Freestuff section here. Search thru the clothes & conforming figures for items (like the bullet proof vest?) that appear to have a leather texture similar to what you have in mind. Download & load the item. Go to render properties & jot down the settings, reflection, transparency, etc. load the item you want to work on. Try duplicating the settings & look over results. Repeat until you find one you like, or feel comfortable enough to try a few of your own. Good luck! (I'd load one & post a screen shot for you, but I'm at my shop, & don't have poser in my laptops - sorry)