5 Lessons by Ben Hogan is one of the best instruction books ever written. It is solid fundamentals, very easy to read, understand, implement, and is the basis of the modern golf swing taught today.
I give a copy to all my students who wish to use the modern 2-plane swing. It is very inexpensive around $9 new at book stores and can be had used for $3 or $4 on the internet at places like Amazon and E-Bay.
Perhaps an even easier swing method is the 1-plane swing aka Moe Norman or Natural Golf. Students usually pick it up with 1 or 2 lessons. Best of all you can learn it for free on the internet by registering at
Moe Norman Golf Academy
Edited to add following comment:
Now with that said you need to be very careful teaching yourself because what you think or fell is going on can be far from reality. Using video of yourself can help, but only a trained observer can pick up on what is causing what to happen.
I teach a lot of people and a good example was a new student last week cam to me for help. I had him take a few swings and immediately saw a few problems like weight being on his toes, starting the downswing from the top, and a reverse pivot. He did not believe me until I showed him the video.
You could clearly see his heels off the ground, chopping wood with an over the top start on the down swing, and his weight going left on the backswing, falling back right on the downswing, then back left on the follow through. It was a mess of a swing all of which he thought or felt was not happening. Well I am still working on this guy one problem at a time because he taught himself and the moves are deeply ingrained into his muscle memory. What I have him doing now is completely foreign to him and basically he has to forget everything he thought he knew about his golf swing and start over again.
The point here is unless you are naturally talented, there is only so much you can teach yourself. Not many touring pro's can even do it on their own.