Boiler rat suggested a good one. If you don't have the explosive badges, just go to a knife server, and if the server admin isn't an ass - ask him if you can kill people with the RDX to get the last few points to rank up. Otherwise you can gun in the titan guns, but that's kind of a lame way to get it.
If everything else fails, just grief in some servers (RDX in knife servers without permission, heavy weapons/vehicles in pistol servers etc.). Hope that helped.
I'd say pistol servers, it's way faster then knife servers.
Basicly, you sit in that one map that i can't remember the name of, also used for knifing, but a very small tight space where everyone fires through, you can shoot people, or revive people, which will eventually give you more points.
If you do not like these ideas, i would suggest at the beginning of the round head to the enemy titan, destroy the four guns, this will give points as well as a badge, then defend your titan using claymores and grenades, this will get you the titan defend badge, and explosive badge.