The medic is one of those "mediocre" classes.. that is until you learn the full potential of this class. The medic is an excellent support class and makes an excellent roaming defender. The fact that the medic can pump-up players health while wandering about, infect enemy and can chase invading players in a similar fashion to the pyro makes him an often underestimated part of a defensive team. The medic comes equipped with a bio-weapon, super nailgun, super shotty, normal and concussion grenades, decent armour, regenerating health and good speed.

General tips

• When healing a friendly player a single swipe with the bio-weapon will bring them up to full health, further hits increase their health above their maximum by 5 points per hit. This extra health drops down to the normal level over time.
• The bio-weapon infects enemy players with a "tropical disease", that will infect any player who comes into contact with the infected person. This is especially handy on public servers when you are attacking and can often cause the enemy to switch their classes to overcome your actions.
• Concussion grenades are excellent for their normal use of concussing the enemy. Another advanced use for them is in "concussion jumps". Using this tactic you can often reach areas not normally accessible to get around enemy defenders. This is used extensively in well6 by skilled attackers.

Offense
The medic can be a real pain to defenders when on the offense, infecting them with the bio-weapon and generally causing havoc. Often the medic's role is a simply to concussion jump up to an unexpected place and capture the flag. This is normally done through using a concussion jump to bypass the defenders, concuss anyone else that manages to get in the way and kill any sentry guns using normal grenades before nabbing the flag and getting out of there.

Defense
Roaming defender is probably the best role for a medic on defense. Moving about pumping up the health of team mates and assisting at any enemy intrusions. A favorite tactic is to concuss someone just as they wander into a sentry gun :)

Aliases and commands

Quick heal:
bind X "impulse 1;+attack;wait;-attack;wait;impulse 5"

Toggle noaim:
Us autoaim (noaim 0) if your target is close, if he's far away, turn off autoaim (noaim 1)
alias noaim1 "noaim 1; echo noaim_off; bind X noaim0" alias noaim0 "noaim 0; echo noaim_on; bind X noaim1" bind X "noaim1"

Attack & Forward ID:
ID command is a good tool for medics because it displays the health of your teammates.
bind X "+attack; id"
bind X "+forward; id"

Gren timer:
alias primeone1 "primeone; play Gren.wav; bind X throwgren1" alias throwgren1 "throwgren; bind X primeone1" bind X "primeone1" alias primeone2 "primetwo; play Gren.wav; bind X throwgren2" alias throwgren2 "throwgren; bind X primeone2" bind X "primeone2"
For the gren timer to work, you'll need to download this zipped wav and unzip it into your Quake/fortress/sound/ directory

Class binds:
bind X "reload" This will reload your weapon.
bind X "ID" This will ID the player. and if he is friend or foe.
bind X "saveme" This will yell for another medic or an engineer.
bind X "inv" This will tell your inventory of grenades.
bind X "discard" This will drop stuff you don't need.

Other resources:
UKFN Tactics for Medics
The Clinic
TF Guide class strategy for Medics