Martingale can be regarded as the best known strategy both for sports betting and gambling in general. It implies doubling your bet after every loss, until you finally win. Despite it`s fame, this system is not so profitable.
With sure betting, you want to find best value in odds at different bookmakers and place your stakes so that no matter what the outcome is, you will gain profit. The system is solid, but it`s very difficult to use properly.
Kelly Criteria is more of a moneymanagement strategy, but it can be used effectively as a betting system. It is based on odds mathematics, value betting and, as said above, moneymanagement. Kelly criteria optimizes your stakes, minimizes your losses and many punters would agree that it gives you the best chance of winning.