As the title implies, I'd like to learn how to play pyro better. I'm pretty good at most classes (aside from heavy, which I avoid on general principle), but I have trouble with pyro due to average health, and being truly effective only at point blank range.

Just to be clear, I'm not a W+M1 pyro. I do know how to use the airblast reflection (although I'm still working on mastering it), about using the shotgun for mid range, and the axtinguisher for quick melee kills, but I see expert pyros out there who come out of seemingly nowhere, and end up performing a lot better than I manage. However, the techniques I see them perform aren't particularly different from what I do, the only change I can detect is that they tend to come from completely unexpected angles at opportune moments. (If anyone needs to know, I use the Degreaser, the shotgun, and the axtinguisher for my pyro loadout.)

So, what should I do to improve my pyro game?