Probably one of the better starting books the "The Black Powder Accuracy System" by Dutch Schoultz. This will cover target shooting, round ball sizing, patching material sizing and care and cleaning of the muzzleloader. It is focused on percussion rifles, but most of the information is applicable to flint lock shooting. Dutch didn't really cover paper patching or conical bullets. Yes, Dutch has passed away, but the system is still available, and I do consider it well worth the asking price.
https://blackpowderrifleaccuracy.com/
With respect to the many Sam Fadala books, the articles on shooting tend to lead one to overload the rifle, but Sam was hunting game at long ranges that required more powder and a heavier ball than many of us need for our shooting experience. The different editions will have the same information with little difference from one edition to the other. GEt the cheapest edition you can find. The early Lyman books from the 1970's and 1980's are great with information is still applicable to modern shooting although these were written before Swiss, Schuetzen, Olde Eyensford powders were available and has limited information on Pyrodex and no information on the other substitute black powders.
Look for the Black Powder Gun Digest books. Basic information is similar from edition to edition. Some new material on new equipment will be presented.
Continue the browsing on the Forum. You will have to critically assess the information presented as regional and personal preferences get included. The Tables and useful information will be helpful and has been fairly well vetted by the moderators and while some information is kind of outdated, still a good starting read.
The Videos by Duelist 1954, The Black Powder Maniac and a few others are worth spending time watching.
If at all possible, meet up with members of a traditional muzzle loading gun club to get the local insights to successful muzzleloading.
