Suggestion: Instead of it being two set teams, maybe make it so players can create teams for a certain amount of money & can join teams. Originally players are on a team by themselves, and they need to either join forces with another team, or they're stuck fending for themselves.
Every kill they get they get Money which can buy better guns/armor/perks like speed increase or they can buy team upgrades which boosts the team's stats slightly.
Teams should have a maximum of 1 member per level. Level 1 = 2 members, level 2 = 3, level 3 = 4, so on, so forth, however team captain can purchase extra member slots.
Team Captains can ally other teams and gang up on one team.
This promotes players being more than just players, it helps everyone become friends and be more social of a community.