Here is a list of books that I have read or am in the process of reading. For now it is just a list but I will write a little more on each when I have more time.
The Financial Spread Betting Handbook: A Guide to Making Money Trading Spread Bets
If you only read one of the books in this list then this is the one I would recommend the most. It takes you through the whole process of spread betting. It explains about various types of stop orders, position sizing and even gives you some strategies to work with until you find your own way in spread betting.