While a simple concept to understand, shooting has nuances that, once learned and practiced, can make it a far more effective technique. The first of these is timing: Extra line is allowed to slide out only AFTER the rod has stopped (after the cast has been made but before the line falls to the water). However, the trick for maximizing a shoot is to release the line as SOON AS POSSIBLE after stopping the rod. If you release too early, the line will simply slide through the rod guides as you move the rod through the air, resulting in a cast with little or no energy. If you release too late, the cast will have fallen partially or completely to the water, and thus is no longer carrying any momentum. And if you have no momentum, you have no shoot.
One of the simplest ways to practice good timing is to talk to yourself as you cast. Say "Stop. Shoot". The "stop" corresponds to stopping the rod at the end of the casting stroke. The "shoot" corresponds to allowing the line to slide out through the rod guides. To have a good command of the process, practice "stop......shoot", then "stop...shoot", then "stopshoot". By starting slowly and getting faster, you'll obtain a better grasp than if you just try to do everything at once.
Now, simply letting go of the line and hoping for the best as it snakes up through the guides is asking for some real control problems. So, to keep everything under control, just make an "O-Ring" with your line hand as you allow the line to flow out (just like the guides on the rod). I typically make an "O-Ring" with my thumb and forefinger. Once the line has shot as far as you want or no longer has any forward momentum, you can just close your hand on the line and you have it--no chasing it around. At that point, you can do whatever it is that you need to do with the line (slip it under a finger of your rod and start a retrieve, etc.)
In addition to good timing, and "handy" control of the line, make certain that your extra line (often called slack) is in a good position to be shot. Line that's tossed uncaringly on a boat deck, or tangled around your legs as you wade isn't likely to shoot all that well. Holding line in large, loose coils (or even in a stripping basket), or spread in a clear pattern on a boat deck, or having it on one distinct side of you in the water will make your shooting life much easier.