I would start by buying three books:
- the Leatherworking Handbook by Valerie Michaels (she guides you through projects, step by step, starting with simple projects, leading up to advanced projects.
- the Art of Making leather Cases: Volumes 1 and 2 - perhaps three, later on.
Start with the stitching methods in Michael's book. All the case making techniques you will need are covered in Stohlman's books.
Also, you tube has gobs of info: check out Leodis Leather and Nigel Armitage - lots more, but sometimes it is tough to sort out the good stuff from bad.
Tools: buy quality, for sure.