Easy Base Stealing:
If your runner is on first base and has decent speed, take two or three lead off 
steps. As soon as the pitcher's arm moves to throw, press Up + Square. If the 
pitcher throws to first base, once the ball gets to the first baseman press Circle to 
go back. If he does not throw, you should be safe at second base.

Easy Fly Ball Catches:
When you are in the outfield and are not sure where the ball is going to land 
because of the wind, the outfielder will lock on the ball to make an easy catch. This 
only works under the rookie difficulty setting.

Stealing Home:
If you have a fairly fast runner on third base, start to steal home. Go back when 
the throw to third base goes home. You will be safe almost always.

Building a good team:
Start a franchise or season. When you get to the season, go into the "Edit" 
category and select your player. Choose to move the player to another team. You 
then can have any desired star on your team. After your first season you will lose 
some players due to the fact you will be over budget, but you can do this trick 
again. To get better ratings for other players, do the same thing by selecting a 
player and then editing the desired category up or down.

Get ejected:
Hit a player while pitching three or four times and you will be ejected.