Rather than spending cash on increasing your entire team attributes, make your centre forward and goalie as powerful as possible. Then save up your cash and buy star players as soon as they are offered.
Put the first player as centre forward where he should be able to outrun all other players and also kill a few opponents every game. Just with your centre forward strong, you should be able to win the second division. Keep buying players and replace your current ones.
Always go for the score multipliers first, and if you need a few quick points, hit the stars and bounce domes. If you position yourself a few pixels away from a bounce dome, you should be able to throw the ball to hit the dome twice with each throw. If you throw the ball quick enough, the opposition will often get beaten up at the same time so you can amass some quick points.