JD Artot's “24 Melodic Etudes” is an intermediate to advanced set of studies that target the technical side of trumpet playing. These develop increased finger dexterity and lip flexibility while being very musically satisfying at the same time. They are idomatically written and sit very well on the instrument, unlike many others that have been adapted from other repertoire instead of expressly composed for the trumpet.
This is a great set and definitely worth a try. You can grab the first few pages for free on the left, then grab an immediate PDF download above.