Larry Wise has several tuning books. They are excellent, but are pretty dated. Bow design has moved so fast, that books have a hard time staying current. Be sure to get the 4th Edition since it has a chapter on hybrid cams.
The Easton Tuning Guide is good, but it is also getting a little dated. Still excellent for tuning arrows, but not so much for tuning bows.
George Ryals video is more than worth the price, but doesn't cover all of the problems that tuners often run into.
Nuts & Bolts of Archery is good. And like the Easton guide, it's a free download. Lots of good information.
Start with the Easton Tuning Guide and Nuts & Bolts of Archery. Both are free. Then like 1track suggested, search this forum for specific problems.
Then save your money for a bow press.
George's video and Larry's book are excellent and you will eventually want to include them and others in your tuning library.
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