Summer break is a great time to clean your brass instrument..
With thanks to Lucian McGuiness for his great advice on how to clean your brass instrument in the school holidays:
The easiest way to do this is to run a warm/hot bath, pull your instrument apart and submerge it in the water for 30 minutes. Add a little soap if you wish, nothing harsh or abrasive. Don’t worry, it won’t rust! Afterwards, make sure you give the valves a good oil, the trombone slide a good lube-up and any valve or tuning slides should have vaseline or appropriate tuning-slide grease applied: no valve oil!
At the very least, give your mouthpiece a good boil: bring water to the boil on the stove, and then boil your mouthpiece like an egg: no harm will come of this, only good.