Fabioisonfire said:
Quoting limited to 4 levels deep
Scouts shouldn't present much of a problem because of their low health. Set them on fire at least once and then airblast them away. If you can't reach them with fire, then try and scare them away with your shotgun.
As for heavies, you never want to face them on open ground. You're going to want to set him on fire, airblast him, run behind a corner, and begin pelting him with flare gun shots as he starts chasing you around each corner. Use his speed against him.
You can airblast back anything Demos and Soldiers shoot at you, so they won't be a problem once you gain enough experience.
Also, something that I want to mention is if you really want to be a credit to team, make sure to airblast back ubers. If you see an ubered Demoman/Heavy/Pyro making a run for one of your friendly sentries, start airblasting back either the medic or his partner. If you airblast the medic far enough, his medigun will be too far away to uber his partner.