Ok, here's my method of betting on football.
Looking at the England v Brazil match, I have backed against the draw (layed) at 3.2/1 for 50 quid, which means that IF the game ends a draw, I pay out 160. However, I will be watching the game on tv, with my trust laptop by my side, and when, not if, when a goal is scored (can't see this being 0-0!)...I will then back the result to be a draw. When a goal is scored the odds on the result being a draw will go up, eg to 5/1. I will then back the same 50, which would return 250. That gives me a profit of 90 IF the result is a draw,and lose nothing if it is any other result. This is the good bit...using the potential profit of 90 pounds, I will then spread across ANY result at 5/1 (last odds taken), ie 90 divided by 5 = 18 pounds whatever the result. This is called trading...which I've been doing for years quite successfully on the exchanges.
OK I've simplified it a bit, but I'm sure you get my drift. Good luck to all that have placed bets, and enjoy the winnings!