The magical art of creating thinking is my superpower. Sometimes it comes out in the form of readible screenplays, other times it just comes out all over the place.
As far as making it work on screen I would suggest you do the same thing as you would if the hero flew normally. An actor on wires in front of a greenscreen. Watch some boogie boarding to get the flow down and add a lot of arm movement to make the flying go from awkward early on to smooth and graceful later.
I'd also add a fan and a copper colored, crinkled, constantly moving bounce board. Have these beneath and slightly to the front of the actor to blow the hair and to reflect a subtle shimmering heat onto her. Then when you edit you blur out the area beneath the actor to create a heat effect.
I would suggest shooting the backgrounds first so you can film the hero on greenscreen in exactly the right places instead of trying to match the backgrounds to the captured actor since you'll have a lot of control in front of the green screen that you wouldn't have out in the street. I would suggest you get some unusual angles and things to add interest to the flight. Shot from ontop of a building going down. Shots through the sunroof of a car going up. Do not keep the camera the same distance from the hero, keep it jumping around.
I would suggest constructing 3-d buildings to have your superhero circle. Do this with simple 3-d program to create really fake looking rectangle with actual building photos plastered on each face so that it looks like the real building. Do this to a handful (with real city in the background) and you can have your actor flying at high level as if you filmed from a copter.
The important thing really is to write the details into the script. If our hero picks up someone they will feel the heat, literally, so write that in. If she saves a kid have her throw the kid on her back so he can ride her like a horse. If she grabs a crook have him complain about the heat and have her mock him like a baby.
If you think you can pull something off write it in, but make sure you have backup plans in case it turns out impossible.
RJSchwarz
San Diego, CA
RJSchwarz