I realize you can do a Google search for this type of stuff, but having recommended resources could save time.

Personally, I read The Adsense Code by Joel Comm. It's geared towards beginners looking to make money from Adsense. There are parts outdated (the last version was published in 2010) but much of the information was valid. After reading through the book, I made some changes he recommends to some of my other blogs for testing and have seen an increase in income.