Marvel vs. Capcom 3 without hope or direction. Fighting game site extraordinaire Shoryuken has put together an incredibly comprehensive guide on the new brawler, including videos on basic strategies, tips for playing each character, and super esoteric info on prolonging those sweet, sweet combos.
We suggest starting out with Shoryuken's video series on the basic mechanics of the game. If you have a hard time grokking the execution of Advancing Guards, or the X-Factor Hyper Move Cancel Maneuver, or the Omega Diagonal Pause-Shift Ground Combo Refraction Evasion Technique, you might just have to rely on good ol' button-mashing.
(Yes, we made that last one up.)