Right.... I suppose we could do with a bit more pyro tips then?
1) be prepared to die a lot (or maybe that's just me
2) You see ubers --> push them back with air-blast! Waste of ammo/time trying to burn them. If you can't bounce the ubered guy back (e.g. if they're halfway up the ramp), wait until you can, or throw the medic round, and hopefully they'll be thrown out of range of the person they're charging.
3) If you're playing against a team with lots of medics, consider switching back to the shotgun - If your targets keep getting healed, what's the point? Also, if you've burnt someone and they've run out of range (e.g. scout), you can keep shooting them with something they can't dodge.
4) If you're really close to an enemy pyro, and they have the flare gun selected, I find it useful to blast them out of flame-thrower range, and lay into them with the shotgun. All they can then do is fire flares (just dodge them, or feel them tingle slightly as they hit), or watch them use up their flame ammo.
5) Burn the damn medics! Not just the people they're healing. I've seen too many situations (mostly other servers) where a pyro will go up against a soldier/pyro and ignore the enemy medic that's keeping them perfectly healthy.
6) When taking out sentries, get in close, then circle around while toasting it. This should draw fire away from team-mates attacking from behind you, and hopefully
towards the engineer (to which their own sentry can cause them an embarrassing death).
7) Watch for stickies, and blast them away from team-mates and friendly sentries when under attack.
8) Spy-check whenever and wherever possible, and puff the flame-thrower occasionally in front of team-mates to prove you're not
Might seem pretty basic, but its a little bit more involved
than sniper ("Use gun on man").