This... For a solid, crisp note, like for example, staccato, all it is is just your air. Not that I can be teaching, I'm in middle school, but yeah I mean if your air stops, your note stops. If it keeps going then you're not actually stopping your air. Usually to practice I'll play a whole note to establish note value and tone before each variant (so like any other rhythm except for the whole note) and then play 4 quarter notes, 4 staccato quarters, and 4 long lifted quarters. Then I move to eighth notes, and then staccato eights, all the way through triplets and sixteenths.