You can never have enough method books as a trumpet player. There may be many books about the same things like buzzing, long tones, articulation, lip flexibility, and more. However, each book has it's own unique take on the subjects and offer different ideas for your practice. Money is limited, but when you have the time I suggest you add these books to your collection if you haven't already. I will list some of the books I think are essential to beginning and intermediate students. If you click the images the link will send you to an external webpage where you can purchase the book. A quick tip for music buying, Amazon is always great, it's also faster and great to support local if you have a music store near you. However, if the books are not in stock, look around first. Music publishers have been pretty slow over the past few years, if the book is out of stock it could take months for them to get another in stock.
Old Trumpets and Inspections
A tip for anyone out there, have your instrument inspected by a professional every now and then. Trumpets are so varied, and once you get used to one it's hard to tell there is anything wrong. Handing your instrument to a teacher can help diagnose any leaks, inconsistencies, or manufacturing issues with your trumpet. There is a 99% chance it's you who is making the horn sound bad, but a 1% chance it's your equipment.
President's Own Disaster
At my first audition for the President’s Own, I learned my very first lesson of professional auditions. The lesson was, don’t play too much before your audition. I went with a large group of trumpet players from IU and had to warm up in the dreaded mass warm-up room with 100 other individuals. In that room it was easy to be distracted by, “oh, she’s doing Clarke, I should do some of that,” and “that seems a lot faster than I am taking Variations on America, I better practice that faster.” By the end of my “warm-up” I was spent, going into the audition barely able to make it through the 3 minutes of repertoire on the list.