After finishing a game in Manager mode, you will see the player rating screen. Scroll down to one of your players and press the Circle (player bio) to make his stats appear. When they do, press the Back and your player rating for the entire team doubles. Repeat this until the match experience is full. You will then notice that his stats have gone up by two every match. When his stats for that position are full, swap strikers for your defenders and their stats will go up the opposite way.
In Manager mode, go to the transfer market and sign the best free agents available. After signing them, put them up for sale immediately before their salary gets too high. This is a good way to make easy money because you will not be charged a transfer fee.