Easy Creation points: 
You'll earn points for various feats in a game. Throwing a perfect game socre you 100 points. An easy way to achieve this is to switch the CPU everytime the CPU team is at bat and strikeout on purpose 

Good Trades (at least for you):
When trading in a franchise mode or expansion mode, you'll want to get rid of your older less talented players for younger better players. (You'll probably need to make somewhat legit trades such as a B- player for a B player for this to work). Even if the CPU rejects your offer, just retry and retry. Most likely it'll accept your trade after several offers. If the trade just doesn't same to work, try a different player of the same grade.

Improved Hitting:
Press start after a pitcher throws his pitch. You'll then be able to evaluate where the ball iis headed. Unpause the game and move your cursor. Line up the triangle (the part closest to the batter) for ideal contact.

Ideal Pitches:
The most useful pitches in the game (hardest to hit) are the Slurve (Mark Burhele of the White sox has this) and the Dominate Curve with Pedro.

Restore pitcher's energy - fast:
In a season / franchise / expansion mode, go to the DL and put any pitcher on the 15 day DL and then immediately take him back to your regular lineup. Magically, your picture will have recovered all his energy.

Control homerun replay:
During a replay of a homerun, you can press various buttons to see different camera angles.

More Points:
You can get points for doing various 'feats' in the game. To get 100 points easily you can pitch a perfect game by switching controls every time the CPU is up at bat and intentionally striking out. 

Hitting Help:
After the pitch is thrown press Start to see the ball path and whether it will be a ball or a strike. You can then adjust your swing accordingly. 

Trade For Any Character:
To get any player in season mode, play one game then create a player and make him 6'11" and any position except pitcher. Then set his patience, range, arm strength, arm accuracy, and glove to "D" and hitting, contact, power, bunt, and speed to "A+". When you pick him up from free agency he should be rated "A" (sometimes A-). You can now trade him for "A+" players.