Hit the sentinel head multiple times for multiball
Don't be too afraid of the challenging modes - Genosha Under Siege and Fiery Assault aren't too difficult and can score consistently high amounts compared to the easier modes.
(0.91) A Fiery Assault is recommended as the first mode of the game. Completing "The Future" afterwards allows all sentinel multiballs for the rest of the game to be extended if all balls drain.
(0.90) Save the City can be worth substantial amounts of points. Hit each shot three times (this can be during any multiball) and then shoot the center ramp when nothing else is going on to start it!
Start with Bitter Rivalry since that's the easiest mission, then Stopping a Juggernaut.
During Sentinel Multiball, defeat two smaller sentinels by hitting two shots of the same color. Then shoot the giant sentinel head for jackpots & super jackpot! The super jackpot can be massive!
You're best off softening the Sentinel up just enough that the last hit starts a multiball before starting a mission (preferably the challenging ones since you'd score more points).
Shoot the downtown loop five times in a row off the plunge for time loop skill shots, then hit the uptown ramp to finish the skill shot and add +15 seconds to ball save. This is a very tough skill shot!
Try hitting the X-Jet shot to feed the danger room early on during sentinel & save the city multiballs. The shots in the danger room help boost jackpot values during both multiballs.
A Fiery Assault plays much like New Orleans on Foo Fighters but without the side flipper. Multiball Extension makes a major difference.