Include in your practice drills drawing your handgun from concealment and shooting while you are moving in the clothes you normally wear. If you generally wear a business suit, you should practice in that. If you wear a heavy jacket in winter, practice in that. And if all you wear in summer is shorts and a t-shirt, you need to practice in that. Anyone can go to the range, take your time to assume a perfect stance and fire away, but a self defense confrontation will seldom offer that opportunity. It is easy to execute the perfect draw from a range holster, but you need to practice with the holster you use to conceal your handgun, in the clothing you are generally wearing, while you are moving, while you are seated, and in every awkward position you can think of.