The salary cap is pretty easy to manipulate. If you don't like a player for whatever reason, than re-negotiate his contract so that he doesn't get a signing bonus. Than work out a trade with another team and you won't take a hit against the salary cap for trading him.
Gain levels in your EA Bio by completing specific challenges and playing other EA Sports title to unlock Madden Cards. Unlockable Cards include:

Level 2: #204 Bingo! Cheat
Level 4: #246 1990 Eagles Classic Team
Level 6: #186 Steve Spurrier Coach

One place to garner quick Tokens is Football 101. Run through all of the plays in your playbook to get a substantial helping of Tokens, which you can use to purchase Madden Cards.
To unlock the Cheerleader/Pump Up Crowd Madden Cards, beat the Game Situation in Mini-Camp. The team who you complete the challenge with is the Cheerleader/Pump Up Card you will unlock.

Get Gold in Mini-Camp challenges to unlock Madden Cards. Cards directly relate to the challenges you complete. For instance, getting a Gold in the Ground Attack challenge will yield a Priest Holmes Card. Be sure to get Golds on all of the difficulty levels to collect all of the cards!