To trade a low rated player for a player who's rating is much higher, first turn off the salary cap. Select the player you want to trade for, go to "Edit Player", and change his position to one that he does not normally play. For example, if he is a wide receiver, then change his position to a quarterback. You will now be able to trade your lowest rated player for him. After you make the trade go back to "Edit Player" and change his position back to his original position.
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 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.
To get the 1st, 2nd, and 3rd pick of round 1 in each Franchise draft, do the following. Note: This trick works 99% of the time on Franchise mode on either Madden 2010 or Madden 2011. The probability of the glitch working may be higher if you finish the season with a better record. (Note: this is all has to be done before entering the playoffs.)
Step 1 After week 17's games are completed, go to NFL Standings and find the teams in 32nd, 31st, and 30th.
Step 2 Start following trade to CPU 1st Round Pick (your team) for 1st Round Pick (32nd place team), 2nd Round Pick (32nd place team), 3rd Round Pick (32nd place team)
Step 3 Start following trade to CPU; 2nd Round Pick (from 32nd Team), 2nd Round Pick (your team), 3rd Round Pick (your team) for 1st Round Pick (31st place team), 2nd Round Pick (31st place team), 3rd Round (31st Team)
Step 4 Start the following trade to CPU; 2nd Round Pick (from 31st Team), 2nd Round Pick (32nd Team), 3rd Round Pick (31st team) for 1st Round Pick (30th place team)
When all is said and done, you should end up with the following;
Round 1 - Pick 1, 2, 3 Round 4 - normal Round 5 - normal Round 6 - normal Round 7 - normal
Create a player at the position you want to play at. Make sure he is a rookie and set his overall to 99. Save your roster. Next, go to Career mode and select "Become a Superstar". Next, select "Play as NFL Rookie". Your superstar should be at the top of the list.
With the salary cap off, choose a player you want (for example, Calvin Johnson) and go to "Edit Player". Then, change him to a QB. His rating will drop to 12. Press Start and select to keep the player without saving. Trade your lowest rated WR for him. The trade will be accepted. Go back in and edit him back to a WR. You will now have Calvin Johnson without losing anyone important.