They seem very easy at first, but when doing them meticulously, I have really benefitted. As for actual methods books for free download, I have never seen any that were very good. Many people use the Suzuki for the solos there. The books are under $10 usually and last for months if you take the time to learn them properly. For very beginners I like a little known series called “Spotlight on Strings” I have found that beginners progress quite quickly with it, and they are also pretty economical.