Training consist of 15% marksmanship, 15% gun handling, and 70% mindset and tactics. The latter is a good place to start. Never practice like your shooting targets, they are not targets, they are threats, treat them as such. Never tell yourself you have a weak side, you don't. You have a gun hand and a support hand, and get used to using both. Don't assume that everything on your person will be in tact or uninjured when the battle begins, it might not be. One handed shooting, both hands, one handed reloads, both hands, unorthodox shooting positions, you won't always be squared of to the threat with it right in front of you. Practice shooting 360 degrees with both hands. Don't forget the fundamentals, but even when you practice them, don't practice shooting at paper targets, remember, they are threats and are trying to kill you, treat them accordingly. Develop a defensive mindset that includes, you will prevail no matter what, and you will never give up, no matter what. There have been volumes written on this subject, and many more to come. I know that this just scratches the surface, but if you do these few things, it will help you. Good luck, be safe out there.