we did rough drafts on a simple sideview fuselage, as you can see on the first 3 pages. they were done based on a sideview bitmap straight from the van's website. edited in photoshop, layered and background replaced by clouds. then it was just rough drawing, for each design a layer or two so they could be compared.
once we settled in one direction, we started developing it in 3d and looking at the details (wingroot fairing, gear legs, empennage fairing etc...) you want to try to keep color transitions mainly on the bigger parts of the airplane. that makes painting e.g. the bottom wing access covers, wingroot fairings, elevator trim tab etc... much easier if they're one color only. and sometimes by shifting one line just a bit you can save quite a few headaches.
in our case we ended up going for all blue flaps and ailerons as well as all blue gear legs just to keep it simple.
also, we found that a dark bottom/light top greatly helps to take away a bit of the rv "boxy" look. same goes for some kind of wave/forward slant main element. a forward slanted line will suggest "speed" kind of like a dragster.
then we started transforming the idea into 3d. this was done using the original paintkit supplied by the now defunct "flightfactory simulations". they had a small payware RV-7A model for fs9 (microsoft flight simulator 2004), which although not top-end quality in every aspect, was pretty good and certainly good enought for this purpose.
basically, almost every flightsim model can be "repainted". in this case this was however simplified and a better quality achievable since the company also released a "paintkit" for the model, which included all the original layered photoshop files. so we were e.g. able to draw our design below their superimposed rivet lines making for a perfect quality repaint.
also, although the final files are in bitmap format, the layered psd's allowed to use vector paths, making shaping and tuning and modifying the curves easy.
then the combined bitmap had to be exported into flightsim format, and a new "variant" of the model added in the flightsim aircraft.cfg file using the new textures.
when the new flightsim X came along, the model wouldn't automatically install and the panel/gauges no longer work. i however managed to at least get the external model ported and working for the paint design purpose.
the advantage of having the different variants now in fs-x was that with a simple switch in the aircraft selector, the different repaints could be tested against all kinds of backdrops, from every perspective angle and even sunrise/sunset/weather conditions.
of course there are easier ways to get to a visually pleasing paintjob ;-) but as with everything in airplane building, sometimes the way is also part of the goal ;-)
if anyone wants to try it themselves, feel free to contact me for additional help.
rgds, bernie