Weathering - as I found out - is a bit of an art form. It's not as simple as just 'dinking' up your AEG with a few scratches and scuffs - and you certainly don't want to be dragging your AEG through the muck or leaving it out in the rain.

I did my first weathering job this week, and learned a lot. But, the main thing I learned is that it's definitely not simply a case of 'start sanding and then stop when you feel like it'. You really do need to have a plan, and preferably a reference photo to base your job on...

 I didn't for this first job, and as a result I wasn't so happy with my work once I eventually did see a reference photo of what I later decided was what I really wanted to achieve. Did that make sense?

Weathering indiscriminantly means you don't really know where you want to stop - and by the time you do decided to stop, it's probably already too late. In my case, I over-weathered a couple of parts which I'm now dissatisfied with - but my only option now is to respray the parts or replace them and start again.

The best advice I can give before you start your project is to decide where your AEG saw service.

What I mean is, say your AEG is an AK47 - did your AK see service in the Russian Army in Europe, or was it a gun owned by a militia in Central Africa? If it was owned by a untrained militiaman, it's likely the AK may be uncared for and abused - it's probably had several users, all of whom probably neglected it. So, you'll want to weather and scuff your example very heavily.

Importantly, take care when you decide to do this - once you weather for a particular state of disrepair, you then can't use that gun for another loadout. So, if you only have a couple of guns, that will have to do you for several loadouts, maybe think twice before applying heavy weathering.

Start small - a scuffed edge here and a scratched piece of wood there - stopping at regular intervals to check the over-all effect. And remember, less can be more.

Link > WWII Airsoft Association - 'Weathering and Aging How-To'