Really nice style! I'm not a manga fan, but your style is a bit different from lots of stuff I see around. Keep it up!
To answer your question, I can think of at least two elements that can both give birth and doom to a great action:
1) Complexity: if you set up a nice, even long complex fight, you'd better keep it clear. Who's fighting with whom and the fight sequences should read and flow really well. Too long or overly complicated scenes and you'll lose your readers
2) Keep it believable: no matter if you go for Star Wars battles or hand-to-hand combat in a jungle, you need to know your combat stuff. For example, learn how a proper kick is thrown and what a laser should look like. Once you've grounded that, you can come up with anything you want, including warping reality (e.g., a little baby may zap people just with her mind ray)
If you'd like to have a look, here's my sci-fi/action/adventure/drama story, The Green-Eyed Sniper 