As with any campaign, I think discussion with everyone about what sort of campaign you want, who the PCs are, and what they do, pays huge dividends. Focusing the campaign early so everyone knows where you sit in the superhero spectrum is pretty important. And finally, variety in what the PCs have to deal with - I think it’s crucial to have plenty of heroic stuff to do, not fights but rescues, dealing with natural disasters, and so on, and since many superhero RPGs don’t have good rules for this, I fond it very helpful to research real life disasters, work out how they would translate to the game mechanics, and think about how the PCs might have been able to intervene.
For instance, a recent campaign (about 5 years ago) was set in Christchurch, NZ, 40 years in the future. So there was a lot of tech development and futurism to discuss, as well as my filling in what Christchurch (renamed Peninsula City) might have become in that time, especially based around the nascent NZ rocket industry. The PCs were heroes, but as defined by the players, superheroes and villains were basically sport teams entertaining people with set piece battles in stadiums - that was their day job, nobody who developed powers seriously considered becoming a criminal given the amount of money you could get from being a commercial super-person.
The main natural disaster was an earthquake that caused the collapse of the TVNZ building, based on similar events during the actual Christchurch earthquake in 2011. The players really enjoyed that session, I think.