Go to the Creation Zone and select "Create New Player". When creating a player, make him a rookie then select a team. When it is time to rate your player, set him to 99 in all attributes. When finished, go to Superstar mode, select "Use Rookie As Superstar", and find your created player from the menu.
In Franchise mode off-season, after re-signing your players, save the game and enter Free Agent mode. If you do not like the free agents available (for example, if you need a top wide receiver and there are none), reload the game until the players that are available are ones you want. You can also do this to make your division easier. For example, if you are the Jets and Randy Moss goes from the Patriots to the Rams then you do not have to worry about facing a player like that twice a season.
When re-signing players, go to your "Player Management" screen first and change the player that you want to re-sign to another position, such as a kicker or punter (the worst overall possible). Go back to re-sign that player for much less. Note: You cannot save the change unless you have enough players at that position after you change the player's position. For example, to change a cornerback to a kicker, you must have four other cornerbacks remaining.
In Franchise mode, you can avoid receiving bad draft picks by trading your picks for the draft picks of the team with the worst record just before the week 6 trading deadline. The CPU will always accept. Alternately, wait until Week 17 then, turn off the trade deadline in your Franchise mode settings. Make the swap for a guaranteed First Overall pick and then turn the deadline back on so that no CPU teams can trade draft picks.