I'm not a fan of the whole rivalry between Marvel and DC, and I'd rather it just disappeared forever and we learned to be friends. However, it is undeniable that, being the two biggest producers of superhero films on the block, the companies are both competing in order to be the bigger money-makers. However, Marvel have the head start and are undisputed "kings of the castle" at the moment. That being said, here are three ways that DC can set themselves up as worthy challengers to the throne.
1.) Be creative
Batman v Superman, Suicide Squad, Justice League: Dark and a Booster Gold-Blue Beetle team-up: these are all really different, interesting film ideas that I'm looking forward to seeing on the big screen. Marvel hasn't made films of that ilk before, so it's good to see DC take a different direction on those fronts. However, that's forgetting the plethora of generic solo and team movies like Justice League Part 1 & 2, The Flash and Cyborg. Marvel has cornered the market on making these types of superhero films, and, honestly, I'm even getting a little sick of what they're releasing. So branch out with your film genres and create superhero films that are fresh to the general audience and geeks alike.
2.) Scrap the release slate
I have three massive issues with DC's film plan for the next five years. The first is the aforementioned lack of imagination above. The second is the foreknowledge of the plan for each character. For example, because Cyborg has a movie planned for 2020 he's free from danger in the two Justice League films. It sucks tension from the films and restricts what the writers can do with the characters. My third problem is that there are just too many films. One a year is enough movies to be going by, and two films every twelve months is just asking for me to get sick of your expanded universe.
3.) Use the bottom of the barrel
I can't imagine that there are many people who have heard of heroes like The Question, Mister Miracle or Kid Eternity. Yet these are just three of the many fantastic obscure characters that DC has kicking around. Similar to what Marvel did with Guardians of the Galaxy, you could revitalize these characters for the big screen. What it means is that you have tons more potential in your universe because you've opened the door for heroes of all shapes and sizes, leading to a variety of genres opening for you to stop your films from getting stale. It also gives writers more freedom with the characters as their fan bases are much smaller and thus more open to change since their characters aren't as iconic as ones like Batman and Superman.
I want to be excited for the DC Expanded Universe, and if they follow these pointers then I'm sure they will be.