I think the must important thing with a comic cover is that it reflects what the story is about and that it stands out on the page amongst all the other covers.
When I first made mine I found a tip here of taking a screenshot of the page and find similarities, and which covers that draw you in, and take inspiration from that. also which you glaze over and NOT do that.
Atm I feel there are many head shots and couple inages going on on the front page, so maybe stear clear of that?
Hope that helps!
Anyways, here are my covers for the Changeling's Sister :3