Here's one way to think of practicing, it's a little like playing frogger...
Not the first part (with the cars) but the second with the lily pads. Well, at least sort of...
Suppose you're learning a new technique like......double tonguing. You can think of each stage of the learning process as a lily pad. You hop from lily pad to the next.
Start with something natural, like saying "da-ga-da-ga" quickly.
Now blow air against your hand using the same syllables.
Now buzz it on your mouthpiece.
Now play it on one note on your horn.
Now play it with moving notes.
If you get stuck on any one lily pad, simply jump back to the lily pad before. If that doesn't work, jump back again.
Just don't tense up and fall in the water.