Clean your instruments people!
On several occasions I have had people come in wondering why their instrument isn't working. The keys are stiff or it sounds weird or pieces are getting stuck. The solution I found almost every time: clean the instrument. It's as simple as that. I've been seeing a lot of nasty instruments this summer, which I'm pretty sure is not a good thing. If I have to clean another nasty trumpet, I'm going to lose my mind!
There is definitely no excuse for a dirty instrument. I have cleaning supplies stacked to the roof for this back to school season. Every instrument.
To all you brass players, just using the spit valve is not cleaning. I have trumpet, trombone, and low brass supplies.
Woodwind instruments get extra nasty! Clarinets, Flutes, and Saxes have all those nice nooks and crannies for gunk to build up in. Clean it!
Even you string players. Make sure rosin doesn't build up on the body, strings and bow.
And remember, your cleaning supplies are like a toothbrush. You wouldn't use the same toothbrush for years and years. At the very least, replace them every year. More if you play often.
Please, please, please clean your instruments.