This is experimental tactic I usually use for even getting to top #1-3 in 12-24 player games. Note, that I just tried it in demo, and I am quite new, but I think it is very effective.Ingredients:
Technician
Stealth Tank
Basic Driving and Shooting skills.
At the beggining of the game get Technician as soon as you can, and start mining obelisk and entrances to the base. Remember about 30 mine limit. Once you hit $900, immediately go for Stealth Tank. Set your weapon to repair gun.
Next stage: use advantages of your invisibility to ambush infantry and light-armored vehicles. I don't recommend getting too far away from the base, unless you really need to.
Usually there is heaven of targets. All you need to do is wait for the right moment, then release few missile salvos and *boink*.
What's different about this tactic is the fact that you can raid large groups of tanks and do drive bys with little penalties to yourself. This tactic involves a lot of running and dodging in vehicle, so be prepared. ZigZag from side to side when running, and start running as soon as you received your first hit, not shooting. Wait until stealth kicks in, pull behind rock or some other >>You are sure it is<< safe place, jump out and repair. It takes maximum 4 seconds to repair and jump back in tank, which is not enough for anything to lock on you. Keep strafing around the tank just in case there is some havoc or sakura shooting through it. Once repaired, get back to ambushing, doing hit and run.
About effectiveness--newbie like me on map CnC Under gets about 10 kills in 5 or so minutes along with countless saved teammates and 'support fire' points.
-Nox.