This thread has some good reasons why, after you get your CHL, it's important to get further training in using a handgun for self defense. So many people get a CHL and a holster and start walking around armed, with maybe 5 minutes of practice in actually drawing their weapon (in the bedroom, most likely).
A good gun defense class teaches actual gunfighting techniques. Stances. How to draw and fire QUICKLY, especially when your gun is inside your waistband, under a zipped winter coat. How to clear a jam instantly. How to turn and fire 90 degrees to the left or right, or 180 degrees to the rear. How to fire with your other hand. How to shoot while running, and again to the front, left and right, and how to reload while you're doing it. You get the picture. Getting a CHL is really just the beginning, like passing the written test in Driver's Ed before actually driving the car.