If its your first time and its for SA then you will probably get an SSRI. The usual first SSRI's are Paxil, Zoloft, or Celexa so you will probably get one of these.
There is no preferred SSRI but Celexa and Lexapro seem to have to least side effects overall.
They might also give you a tranquilizer if you have panic attacks or panic like symptoms of anxiety. These tranquilizers are usually in the benzodiazepine family called benzo's for short. My favorite one is Xanax but the only really difference is in how long they last and how long it takes to feel.
In my case Xanax starts working really quick but also wears off really quick. This is what I need because my anxiety is really intense and I need something that takes effect quick.