Here's a tip for French and American comic book writers:
STOP putting in dialogues everywhere in action sequences! A character can't deliver a 5 second existential dialogue when an action takes 1 second to do. It removes the sense of effort, weight, speed and credibility of an action. Too often do I see comic books have a line per panel while characters are struggling in an uninterrupted battle. Sometimes a character swings his fist in 3 panels (a 1 second action) and manages to tell all about what he did in detail for the weekend during that single punch. Bravo! You managed to save a few panels and to weaken both your story and your action shots into an unmemorable mess. The action doesn't flow and the dialogue is unconvincing. It makes everything less dramatic.
RYTHM. You need rythm in action sequences. You can still deliver dialogues, but make it believable. Action sequences don't have to be a flowing and uninterrupted string of movements; in fact it's boring if you don't have a bit of pauses here and there. Like a story, it's all about pacing. Just look at the classic of action combat comics, Dragon Ball: they pause to talk a few seconds when taking their breath between series of moves. Even movies use similar pacing because it just doesn't make sense otherwise. If your characters are running, they yell, not talk. It's actually hard to talk when you sprint. You don't deliver a monologue when you pounce on your enemy, but you might once you pin him down and have the advantage, you know, when you can actually breathe and think about something else than swinging your fist. Dialogues are better inserted during pauses, blocking, or whatever movement which allows you to breathe and think a little. You can even use expressive reactions to insert a few lines. Otherwise you're just cramming stuff together into an unexciting mess. It's better to have two pages of dialogue with a single cool action move than to fill up two pages mixing dialogues and actions.
The exception would be if you use a narrator, as narration tends to be timeless. It will slow down the action flow but comics using narration always seem more like thoughts that bends time anyways, so you pretty much sacrificed the sense of urgency to begin with.
I was reading this comic called SpyGames by Jean-David Moreau and Kim Jung Gi and it was the drop that spilled the bucket; I just had to react. In my opinion pacing is what separates good comics from great comics.
So that was my Sunday Morning advice!