Make sure you use the right cleaning and maintenance products for your instrument. You can get most things here.
Every usage
Check that the valves still have a sufficient amount of oil on them
For trombones, ensure that the slide is well lubricated
Wipe the instrument down after play with a proper cloth
Every two weeks
Take the valve out of it’s casing
Wash this down with warm soapy water. Make sure any residue is removed
Give the internal casing a wipe down with a damp cloth and a cleaning brush. Make sure both the valve and the casing are dry
Put a few drops of valve oil on the bottom section of the valve, spinning this to make sure the whole surface has a thin layer of oil
Replace the valve and repeat with the others (one valve at a time to avoid any confusion)
For trombones, wash the slide with warm soapy water. Dry it throughly and reapply your slide oil/cream.
Give the mouthpiece a wash with warm soapy water using a cleaning brush
Every few months
The instrument will need bathing to clean the inside.
Fill your bath with warm water and washing liquid (not a great deal needed) so the instrument is partially submerged
Take the valves, mouthpiece, valve caps and tuning slides off the instrument and leave them to soak in the bath for about 20 minutes
Take a cleaning brush and clean the valve casing, valves and mouthpiece thoroughly.
Rinse the instrument thoroughly, making sure that there are no suds left
Dry as much as you can. Leave the inside to dry naturally
Once dry, oil up the valves (as above), grease the slides and put the instrument back together.
Komen