(Sorry for the long reply)
Look at the map when spawning, and also keep an eye on the minimap for your sides troups I use that a lot to decide where to go.
Also joining a squad lets a squad leader point you in the place to go, and I find squad play far more enjoyable.
As for classes, I tried medic for a while and found the same issue, I think in certin areas of the map its just a pain to find the corpses, but apart from that people appreciate healing, just not everyone is used to their being a medic and tend to run away even with no health while your standing their going I CAN HEAL
The Anti-Tank is actually quite powerfull but its no one shot killer, I 2 teamed with another Anti-Tank and found that very effective. Also depends where you are, Anti Tank on the roof of the hotel, shooting down onto the top of incoming tanks can be quite deadly. Anti-Tank units need to be sneaky and fire from well hidden positions (or downwards) which gives them time as the tank driver looks for them. (shooting at them when the turret isint facing them helps, which is one reason 2 teaming worked well)
I personally have found I prefer the special forces, due to their usefullness in taking out enemy guns and vehicles, though the running up to tanks to place 2 c4s (insta kill) on the tank can be hard, and quite often have decided to blow up the charges early because they have started hitting me, so I take them out and me.
Not sure any of what I have writen helps but hope it helps a little.