As you can guess from the title, this post is all about everyone's favorite class, the pyro!
By far one of the most fun classes to play, the pyro can set everything him/her on fire, and possesses the unique ability to reflect all non-bullet projectiles, from sentrygun rockets to huntsman arrows.
Now, I don't really think a playstyle guide for the pyro is THAT necessary. Just use the degreaser or flame thrower, the shotgun, and either the powerjack or axtinguisher, and you'll be fine. Honestly, the other pyros weapons aren't that good (the backburner, for those of you who are proponents, is just plain silly these days)
However, as TF2 has gotten older, so has its playerbase, and gone are the days were 99% of the pyros out there were mindless idiots who would run at you in straight lines hoping to catch you on fire. Now, people are actively airblasting (reflecting) every projectile back at you, and have a mean flame + melee combo that can knock out a heavy in one shot.
To beat this new generation of pyro, it's important to keep one thing in mind. The pyro is only as effective as its enemies allow it to be. If you try to shoot a rocket straight at a pyro, it can easily reflect it, because you afford it that advantage. Instead, change your objective. Hitting the pyro with indirect splash damage still does a significant amount of damage, and ensures that a successful reflect is much harder. In addition, using your rockets to blast yourself further away from the pyro, and using the shotgun for hitscan damage is a viable tactic.
On maps where there is a possibility of environmental death by falling, players LOVE to airblast you off a cliff. There's really no way to avoid this, except to simply stay away from cliffs. If you're a fairly mobile class, like the scout or medic, you should be able to avoid the pyros relatively easily. However, if you should have the ill luck to be playing heavy or soldier, you are a prime target. Pyros who use this tactic tend to zone in on it, so if any are making a beeline for you, you can pretty confidently guess at what they're thinking.
Good luck against one of the more annoying classes out there!