Greater than 3000MAH worth of batteries.

-A plug for the larger batteries and AKs that use them. Most of the guys who ran high capacity large batteries last year managed to sustain themselves in combat for the entire duration of the event without recharging. If possible try to use a large capacity battery. Keep in mind that you may be forward deployed for extended periods so having a battery go kaput is pretty inconvenient.
-Bring a spare.