I have a lot of scrap leather Jim, PM me and I'll send you some for your kit. For a checkbook cover you want it down around 3-5 oz thickness. I probably have some beginning tutorials I can send also. I bet I even have some patterns with instructions in thst size.
Good and wet while working it, you can only tool veg-tanned leather. Finished leather won't tool. Nicely veg-tanned tools well with burnishers as well as with stamping.
For a first project, if you want to guarantee success, I would use a basket stamp and avoid the cutting knife. A single basket stamp is what you see on a lot if holsters and belts, as well as billfolds.
Tandy was going downhill, fast. Some of the employees had better ideas on how to fo things and started The Leather Factory. After competing for a bit they bought out Tandy. I visited their factory and main showroom 4 yrs ago in Ft. Worth, TX.
The main showroom has a small museum named after Al Stohlman, who wrote all those leather craft books from when I was a kid.
It is a quick sidetrip if you get down around Ft. Worth. The best thing for me is how nice those leather stores smell.
Chilly