I train with people and have learned from people that have real world experience. The first thing they tell you is that you will react out of training under stress. The way you train, from grip to stance to how you reload, will come automatically. Train poorly and you will have poor skills.
I have some experience in competitive shooting, again nothing I want to offer advice based on. What I want to do is point you to other sites and resources that I have learned from. Here's one. Brian Enos (shooting biography here) is a competition shooter who has written some books on the subject and hosts a large website that includes a forum. I will be referencing some of the information there in future posts.
Brian has approached shooting as a martial art. Some of his writing is about the philosophy he has used to be successful as a competitive shooter. This is a book about shooting. Worth reading because he lets you inside his thinking.