Here is what I do:
I have a shelf that has dividers on it with the alphabet letter on each divider. I put the books in the appropriate space. I then use receipe cards and list a book with author on each card and then file them in a little box I made with alphabet dividers. When I take a book from the shelf, I pull the card and put it where I can see that I have a book "out" ( like the library). I also have an alphabetical list of my books in my documents so I can check to make sure I don't buy the same book twice.
There are probably other better systems out there, but this has worked for me for years.