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Find a good place to buy leather. Understand how good leather is sold. Look out for scars, bug bites, and brands. Start by buying cheap, beginner's leather. Buy the right type of leather for tooling. Choose the appropriate thickness for your project.
Common places to buy leather include Tandy Leather Factory and Springfield Leather Company. You can find physical stores in your area but there are also a number of online retailers. Of course, if you find another option that you like better, you can take that option. When looking at places to buy leather, you should look at how they are selling it. Good leather is usually bought by the square foot or by the piece. You can also buy scrap leather by the bag. If someone's selling you leather that doesn't seem right, be wary. Not only will scars, brands, and bites make your final product difficult to tool and look bad, they're also a sign that a leather vendor is supplying their leather from places that treat their cows terribly. You don't want to have any part in animals being abused, so buy your leather from good sources. It is said that writers need to write a few hundred thousand words before any of the words are good. For leather working, you're going to have to do some bad work before you're ready to start doing good work, so you should not start by buying fancy leather. Buy scrap leather by the bag or any other cheap beginner's leather. You'll know when you're ready for something a little nicer! For tooling, cow leather that has been vegetable tanned is the best option. Other leathers can be used for other details, but cow veg tan is your friend when it comes to tooling. You will want to avoid leather that is intended for furniture and leather that is textured. These are not suitable for tooling. Different projects will need leathers of different thicknesses. Make sure you're getting the right thickness for what you want to do. Leather thickness is measured by the ounce. For tooling, 2-3 ounces is too thin. Start instead with 3-4 ounces and use thicker leather depending on your purposes. Weights translate to a standard range of millimeters. You may want to test the thickness of your leather pieces when you buy a new batch to make sure that you got what you paid for.