As for composition, try to keep the gimbal level in the majority of your shot so there's a visible horizon. I found this makes for the nicest images in general, unless there's a really cool flyover to film whilst pointing the camera down.
Also, try to think of a cool shot to make beforehand and always perform it slowly. Flying the quad can be exiting and can easily make you think that you've taken a cool slow flyby that takes half a minute while in reality you zipped past in 2 seconds, so to say.
Another cool trick is to slowly and smoothly fly while repositioning your drone. You'll be surprised how useful the footage gets in between shots when the camera flows smoothly instead of having jerky movement.
Lastly, edit your video in post and cut any footage where you are positioning your quad and just leave the cool footage in. This can shorten a 10 minute video to 1-2 minutes. The footage filmed during positioning usually adds nothing to what you're trying to show, so the only thing that it does is make people lose their attention (which honestly isn't a lot these days), not to mention possibly nauseated if the camera jerks too much and too frequently. Leaving only the interesting parts in will deliver a much better pacing in your video and will keep your audience interested throughout.