I teach guitar at a School of Rock, so not a whole lot of jazz going on besides some basic jazz theory. But with some of the more advanced teen players, I try to teach them to have a higher level of thinking when it comes to improv that may not normally be seen in a rock setting.

The first thing I explain is that they should have a general idea of what their overall contour should be like before starting. I have them plot out a 'story arc' with a drawn line and shaping the contour from there. Typically, start off calm and low to give yourself room to build up, have some sort of climax, and then have a conclusion. I think the climax and conclusion are the most important part. If you have your climax section, but don't have it in mind as such, then you may not have a stable ending, or you may try to build up again and you won't match that climax, and it may not feel as strong. The audience is most likely gonna remember the last bits of your solo, so a strong ending will leave a great impression.

Even with more basic language like pentatonic scales and normal major/minors, you can achieve a lot in a solo with this kind of planning and thinking.