Nowt to it, really... you normally remove the valves to oil them (you do, don't you?!!), then all you really need do is run warm water through it for a few minutes, dry it off as best you can, oil the valves and replace them.

The valves should be 'keyed' to prevent them being shoved in the wrong hole, but even so, the holes through the valves are designed to line up with the tubing, so it should be easy enough to work out which one is which if you get them mixed up.

Any good music shop will sell the correct oil for the valves...

The idea is to try to stop nasty stuff growing inside... yeuk!! Unlike most woodwind instruments, you can't use a fluffy pull-through each time you've been playing!