I often recommend this book. There are different types of OCD and the writers provide an explanation of each type plus ways of managing OCD depending on your type.
I particularly like using theory A, theory B. This is written throughout the book and asks you to find supporting evidence for both theories. Theory A is that OCD is telling the truth and you should do what it says and theory B is that you worry about something bad happening and you should try techniques to manage your worry. This is useful little paperback book that you can dip in and out of, as and when you need to.
- Self Help