Every guitar player should have the book: How to make your electric guitar play great.
It's a fantastic book that shows you how to fix all sorts of issues with a guitar. One of the most used would be how to set up your guitar, step by step. This book transformed me. I was no longer worried about breaking anything. I was able to do my own setups, the way I want it, and not how some random tech liked it. A setup costs more than the book, and sometimes you need a setup done twice a year, depending on climate. Save yourself some money and learn how to do your own setups.