1: Do not re-tweet positive book reviews or blog reviews. Accept the compliment, and move on...don't tell the world how great you are. It's embarassing.
2: If you run two twitter accounts do NOT under any circumstances retweet yourself. Once again...it's embarassing because we all know that you run two accounts.
3: Never, ever under any circumstances set up your own Facebook Fan page. If you're that important that you need a Fan page then become a movie star rather than a preacher man...
4: Do not use you Facebook account to generate content for a new book. If you want to write a book at least make sure that you know what the content is.
5: Do not end all blog posts, tweets, facebook status updates with...'you can read about this in my new book, which is available at the discounted price of £1.99 here'. Once again it's embarassing. If the book is good it will sell.