Currently, the majority of players play as Heroes. This painfully clear when trying to form a party on the villain side vs the heroes side. This then compounds the issue of people playing heroes over villains.
Suggestion: Try various incentives to try and balance the server. IE: An additional experience or infamy passive and always on boost. Reduced prices at the stores. These incentives can swap back to heroes if there are more villains than heroes playing.
I am sure other people can give other/better suggestions on how to help get people on the villain's side.