1. A way to earn gold. I'm pretty sure the only way to get gold (without being a member) is to buy it. Correct me if I'm wrong.
2. Make characters that can ride around using sidekicks look better when riding (No offense but if you have anyone like that then you know what I mean)
3. Have a mission that's X2 in a month. It could be a day, week, month, but they should have a mission thats X2 for a period of time based on a theme (X-men month= X men mission
4. Buying a hero gets you a random potion (Just a thought but hey, potions are pretty fun)
Thats all I got. Pretty lame and some are dumb but just my thoughts.