For a very worthwhile and full discussion of many other facets of trumpet practice, preparation, and performance, check out the whole master class from which this was taken that has been posted on the ITG Pedagogy site as Notes on Technique. Mr. Bilger currently is Principal Trumpet of the Philadelphia Orchestra, and was previously Principal of the Dallas Symphony. He currently teaches at The Curtis Institute of Music and Temple University in Philadelphia. As is the case with range, endurance is also a combination of many of the topics we have already touched upon, and will benefit from many of the same etudes. The two other things that will most quickly improve endurance are efficiency and loud practice.
Efficiency is a necessity for any brass player.
Playing the trumpet is extremely physical, and efficient playing will reduce the demands on the player. Always think about what you are doing while you play 2. Loud practice is another part of trumpet playing that is often overlooked. Remember, when practicing at loud dynamic levels, always keep your sound from distorting, and never cause yourself physical pain. Orchestral excerpts are a good source of loud material, as are the Brandt Orchestral Etudes.