finished all the random pre-reqs for the new assignments (just the kills left to get) so here's a quick how-to;
50 Squad Rez - easy, just play as a fucking squad unlike 99% of the morons that play BF3
25 kills w/ underslung shottie. Not sure if this is just for the M26 or if it includes the 40mm also, but the MASS is still good as a stand-alone shotgun, so just play like you normally would
25 gaymore kills. you can do this grinding on metro, but it's (much quicker) on TDM canals. drop two at a time at the end of a blind corner, wait for someone to lemming into you. rinse repeat, carry shotgun to mop up anyone that survives (hitreg can be fucking awful with claymores)
25 vehicle kills w/ C4. this only ticks over per actual vehicle asploded, not number of people in the vehicle. Good way to boost this quick is playing as US on Caspian CQ (48 or 64 works best). camp just outside the ruskie base on the road leading from there to E - lots of rocks to hide in, lots of shady bits to drop C4 on. You can also snag the easy destruction by C4'ing a vehicle if the enemy ditches, as long as you C4 it before it burns out, it counts.
50 sqd MAV spots. this one is very very easy. MAV functions identical to a TUGs when it's not actively controlled, so drop it above or below B flag on metro, or fly it to somewhere inaccessible on a TDM map and leave it.
350m headshot. If you enjoy actually sniping (along with presumably sticking your dick in a garlic crusher) play Oman or Firestorm, wait for some spastic to climb one of the cranes and shoot him. Or be a manly man, accept sniping like that is fucking dumb and just boost it with a fellow internet friend.
20 Mine kills. Caspian again, this might take a while because of FUCKING MINES ARE FUCKING SHIT but basically mine both entrances to hilltop flag, the road between E and checkpoint, and outside the russian spawn. set your minimap to maximum zoom-out so you can watch which ones explode. I found it best placing them in little triangles of 3, with just 2 sometimes a tank would only clip the 2nd resulting in a disable.
5 Air vehicle kills with SMAW/RPG/Jav. Davamand rush is decent for this, the littlebird and z11 generally fly pretty low and slow. Failing that just bully some recon into convincing him his life is fucking worthless, and he can get some slight redemption by soflaming for you on demand.
then you only have to look forward to 100 kills per weapon (do the first set of premium assignments first, otherwise none of this shit even counts) and another 1700 to get the really amazing cool thanks for spending your art time on this DICE you bunch of fucking dicks camos
Small hourglass island
Always raining and foggy
Use an umbrella