Joseph Forestier’s 26 Studies for Trumpet is a wonderful volume of studies, especially for anyone who is not familiar with his 3 volume Grand Method for trumpet (which you can find here LINK). It provides an opportunity to experience his style of writing for the instrument, which is beautifully idiomatic and approachable, without committing to a 300 page progressive method. I do have a feeling though, that after you play these, you will be grabbing his method as well. They are tight and dramatic, and show off a wide range of styles and technical difficulties for the trumpet.
You can see the first few for free to the left, then you can purchase an immediate PDF download above. Enjoy!