As you said... there's not much to look at... Only thing I can tell you: put a sh*tload of work into your characters, make them interesting, make them look interesting, give them something special... Make them unique. And then give them a reason to be in that story of yours.
If you want a good story you first need a good plot. Plot means: why does something happen? and: how is it connected to all the other stuff (characters etc.).
For the bad guys: I think there is a quote, that says: a hero is only as good as his enemy. Means if Superman gets to fight guinea pigs he'll never look like a superhero... more like a total moron.
So bad guys very important.
Now we got the look of your comic. What makes a Comic look good?
Colors: black and white can be pretty kewl (--> Sin City)
If you decide to go for a coloured version, be careful not to become to colourful.
If your Comic is about steampunk and zombies you might want to go for desaturated colours. It's not a must but I think that would suit.
There probably more I could tell you, but it's late (or early however you define it) and I don't get paid for this, so good bye for now