Challenge yourself. If you have been playing amateur for a while and absolutely dominate teams on amateur, go up to semi-pro. Continue this process until you reach the highest difficulty. Also try different teams and different strategies or method of play. You might just be playing with a team that does not adhere to your play type.
Remember there are other passing buttons than A (xbox); dont forget to use other passing buttons like Y and X. Also dont forget that passes can be chipped over the team or across longer distances by hitting the bumper (once again xbox). Really exploit these other passing tools, they are definately deadly. Play fast and vicious. Most medium to low skill Fifa players will be dazzled by quick passing to attacks they dont even see. Lastly, possess possess possess. If the other team doesnt even get the ball, how can they win? Do not force any attack that is probbably futile and will cause you to lose the ball. Play the ball back and reset the attack or play you are looking to make.