The key to victory is money. With money comes might and with might comes more money. For your money you can buy armor, weapons, explosives, special items and many other things. This is where you buy your arsenal. Choose your weapons wisely and try to save a little money to get a bigger gun.
Rifles fire much more accurate and do more damage.
You save bullets and the bullets you shoot travels a lot faster but rifles have a low fire rate. Automatic weapons have a hell of a fire rate but the bullets doesn't go very straight. Good for close combat. There are also explosive weapons. Note that explosives meant for humans doesn't bite very hard at tanks.