Yes being a medic helps a lot. You get two team points for every time you revive someone. You also get two team points for capturing (making it neutral and actually turning it to your team's side. Being an engineer in a blackhawk helps as you slowly but surely get repair points, but you also get the kill assists, be sure to jump out to cap flags and then jump back in for more team point collecting.
Being support or medic in a blackhawk is effective as well, as you automatically resupply people that are chucking grenades or shooting from the other passenger positions, plus the kill assists and flag caps you get.
Now that I think about it, if you're a good pilot, be a medic or support guy while piloting a blackhawk (I keep saying the Blackhawk because... well, you know the BH has much more effective guns then the shoebox that the MEC and PLA team has) you will heal or resupply your BH crew, get tons of kill assists (that's if you give your gunners decent shooting opportunities, and you can cap flags while still being in the helicopter!
Snipers can gain some team points, but not really enough to get a ribbon. Shoot the enemy in the chest with an M95 or M24 which only leaves two bars of health and let your teammates finish him off for a kill assist.
Come to think of it. I am eligble to get the Valourous (I'm Canadian, thus the "u" in the word) Unit Ribbon. I should be using the tips I outline here. :p