Anti-fog. I can't remember the brand a lot of people swear by. Think it was Fog-Tech or something? Not sure. Search around or ask around, either way, you'll get a lot of results.
A decent charger would be the Pirahna Digital Peak Charger. I have one, they're amazing once you get to know how to use it (Learning curve isn't hard, and if you're unsure, just post a thread. You get some helpful advice for what you're charging). Some people also recommend the TLP 4000C (I think that's what it's called?) for a charger. Chargers require a little bit of research, otherwise you may get a crapper.
You may want to get a spare pair of boots, just since wearing regular shoes or just your regular work boots can get pretty dirty. Scavenge your house for some spare ones. Worst comes to worst, buy some cheap boots for like $20.
Midcaps/Lowcaps for sure. Hi-caps can get annoying because after about 20 shots, you have to rewind your mag, where-as with a 100rd midcap, there's no winding, same with a 50rd lowcap, that and some games will say you can only field 1 high-cap, where-as you're able to field as many lowmidcaps/lowcaps as you can carry logically on you.
Primary: Custom WE M16A3
Secondary: KWA MP9
Side: Custom WE M1911A1