First, you should have listened to the solo, as played by a fine player, such as Thomas Stevens, Phil Smith, or Maurice Andre, before starting to play the piece yourself.... This is not so you imitate them, but that so you have a integrated image of the entire piece, not just the trumpet part....

Using a metronome to keep your pace steady (and btw, it goes without saying that you should've been using a metronome to practice the technical studies, eh?), play through the first phrase of the solo, taking care to pay attention to dynamics, articulation and releases....

You want to have the air FLOWing through the musical line, whether the notes are legato, or marcato, tenuto or staccato, the music must always FLOW....

Your valves should be in sync with your tongue and your lips...there should be no blurps between the notes, and certainly no smears (caused by valves being pushed down too timidly)....

Pay close attention to the inner phrase of the music:  let the energy increase slightly at tension points, and relax at resolutions (this comes from Renaissance period practice)....

Think about the musical line:
Should there be a slight crescendo in a rising line, or a decrescendo (either may be valid, depending on the style and the effect desired)....answer other questions as they arise.....

When you are satisfied with that first phrase, move on to the next....
Follow the same process, then add the two phrases together....

Analyze the music to note high points in pitch, dynamics, tension, texture, and use those points to enhance your performance....

Continue the process through the piece or movement (this can become more specific with a particular piece in mind)....

Before leaving this practice session, attempt to perform the piece or movement all the way through, focusing on making the performance as musically sensitive as possible(you might want to tape record this part of your practice, but don't listen to it for a couple of weeks<!>)...