well, another important part with betfair is trading. when you have the possibility to green up (when back value is higher than lay value) you should use it, especially if you are unsure about how a match is going on right now (imminent draw?).
for example: you lay @4.6 5x. at arsenal lead in 80min the value was @9.2 - if you back this value for 2.5x, you can win about 2.5x (from the original 5x) no matter how the game ends.
for example: you lay @4.6 5x. at arsenal lead in 80min the value was @9.2 - if you back this value for 2.5x, you can win about 2.5x (from the original 5x) no matter how the game ends.