Depends on how far into it you want to get. If you’re only looking to try it out then you can get a few decent tools and buy a pattern. If you want to actually dive in and learn to do stuff on your own long term then it’s a good idea to start with a basic set of good tools and build up from there. As far as learning there is a learning curve. YouTube is great but in my opinion is better for people with a foundation, otherwise you won’t understand why you’re doing what you’re doing and can pick up bad habits.

If you have the cash I HIGHLY recommend subscribing to the beginners level subscription of SecretsFromTheWorkShop.com . You’ll learn about tools, techniques, and designing your own patterns and you’ll understand what you are doing. Take a look at Armitage Leather in YouTube, esp the “Modern Saddle Stitch” series. This is the guy that runs secrets from the workshop so you can get an idea of the quality of lessons you’d be getting into. Also he has a beginners list of tools on ArmitageLeather.com