I have done 2 okto games now (2nd in command in the last game) and I think in terms of gear and how you organise yourself these are the ways I do it.
MDF have a forward operating base and you are goiing to want to leave a bag here. It should contain lunch, extra water, BBs, loader, spare smoke and flash grenades and any spare stuff you might need through the day like extra clothing.
On your person you will want your mags, water (at least 1L), snack food, grenades (1 smoke, 1 flash) and your baofeng radio (we use VHF and UHF) with a headset. I also have some spare eye pro and cleaning kit to deal with fogging which does happen occasionally in 8 hours even with my turbo fan. Most of the guys in these games are actually using ballistic glasses not goggles.
I wouldn't bother with a pistol on this site, there is only one place I would have appreciated having one and its just weight and awkwardness you don't need. I think its also worth mentioning that the site that will be used in December does not have any water pipes on it so water is a major concern for the weekend. If you are coming in a car bring water to last the weekend, its a lot of water. The MDF tend to be the first guys ready on a morning and they often insert into the zone on time as well (unlike the rebels who last time were like 2 hours late!) so we go out on patrol and search the terrain and other things before the game has fully started. So make sure you know how your kit goes together, you have tested it all works and set your radio up before you arrive and know how to use it.
Other gear you might want for the evenings and such which perhaps some wouldn't consider is things like a flashlight and batteries, food for the evening (although Saturday night MDF has a history of going to the pub or chinese takeout). I don't know who is in charge next game, not sure if Pete is back or if I'll attend but your commander may want certain things (a watch).
Its a great game, sometimes its standing there with your eyes on the woods watching for movement in a defensive position and other times its all out deadly chaos and everything in between. The radio comms, the story and everything comes together to make it feel very real sometimes. I love the games and I love the comms/command/coordination aspect of these types of milsims.