The new fad in Gundam modeling in Japan is not to see how well you can scratch build or modify a kit but to see how good you can get it to look without paint. The technique used does require a certain amount of skill and probably more courage than taking an airbrush to yer kit.
What you do is get fine sand paper and sand down the surface to get rid of that shiny just-off-the-assembly-line finish. Then you do the panel lines and use some of the Gundam weathering markers to give it the bad n dirty look. Once thats done then its a good going over with Top coat.
Have not tried out this method yet but think that giving this a go on the HCM PRO series is a good place to start because they are not that expensive and you wouldn't end up crying so much if you screw things up.
Scans from Dengeki Hobby and yes I know that Gyan is not a Gundam but Google prefers that I call this article "Gundam Paint" ^o^
And let me quickly apologize to all the new readers who joined since Monday thinking "WTF - the pagination is broke dude!" - some .htaccess problems - its fixed now...