alanback: It's a good idea to read a book (or a chapter) on doubling strategy. Many of the answers to these questions are common sense once you think about them, but wouldn't be intuitively obvious to a beginner. A good example is the take/drop question. You know that the outcome of the match will be decided by the result of the current game if you take, and by the outcome of the next game if you drop. Your chances of winning the next game are 50-50 (modify this if you think you can estimate the relative skills of yourself and your opponent); you should take if your chances of winning the current game are more than that, drop if they are less.