Rinse in warm water thoroughly. Dry with a lint free cloth Swab the inside of the valve casing with a cleaning rod and clean lint free rag. Be sure cover the cleaning rod completely as to not scratch the valve casing. Clean the outside of your instrument each time you play by wiping with a cloth. One little dent in the valve casing can cause a costly repair since there is only one thousandth of an inch between a valve casing and the valve.
Trombone slides have similar clearances.
Do not touch silver sides of valve or place on a hard surface. Never grab an instrument by the valve slides. If it becomes stuck, take it to your director or a repairman for removal using a special tool. You will damage the horn if you try to remove it yourself. Wash out your mouthpiece with soap and warm water at least once every two weeks.