I will teach you some ways to use the medic class.
Quick tip[]
If you have multiple teammates to revive, start with the teammate who's icon has faded out the most. This person will respawn the soonest. Once the body disappears, you can't revive him, and you lose the ticket for good. The more faded it is, the sooner time will run out to revive him.
Defensively[]
I am starting with a defensive method as this is most likely the method the developers wanted people to use the medic as, for defensive purposes. With that aside, i believe the weapon used is pretty much up to personal preference, though i prefer the T88 LMG, MG3, and recommend that the MG36 or XM8 LMG are not used. The M249 is also decent with a red dot sight. You may want to use the M1 Garand or M14 EBR if you will be engaging enemies at longer ranges. Your spec 1 should be the Medic Heal upgrade, though some may prefer using an optic or ammo upgrade. The spec 2 should be body armor, increasing the health for you, keeping you alive. Think, that may be just enough extra health to make it to cover, heal then revive those who weren't so lucky. Some may also use the medkit range upgrade, but i think if people ant health, they would go straight to the pack, which i always place behind cover, provided there is any cover. That said, remember to toss a medpack when a firefight starts, and when it finishes. Also, after the fight is finished or if a brief pause happens, revive your teammates. Don't go reviving teammates in the middle of a firefight, because it pisses off the dude who keeps dying and getting revived. And remember, SPOT, SPOT, SPOT!!!!
Offensively[]
For offensive purposes, you will not want an LMG, except the MG36 or XM8, or if you are a crazed M60 asshole. However, it is a good idea to use soldier unlocks. I recommend using the M1A1 Thompson or G3. You will want to use the Med pack upgrade, again, as sights are normally not needed. With the MG36 and the XM8 LMG, you use the MG36 for its built in red dot, or the XM8 if you prefer ironsights. Otherwise, you will be using a soldier unlock, which can't mount optics. If you feel this is not needed, i would then recommend the Lightweight pack if you are using an LMG. Anyway, your spec 2 should be the med pack range upgrade, or the Marksman training for the weapon you are using. With this setup, you must heal your team when they need healing. If a firefight occurs, try to revive your team, but don't do it when you have enemies shootig at you. Kill them, THEN revive your team. You are supposed to support the team to prevent casualties on your team. When the fight is finished, heal the wounded and revive the dead. Also, remember to SPOT, SPOT, SPOT!
If you have any more tactics regarding the medic class, please comment below.