Well, I may not be any where near as trained or proficient as others, but I have a couple suggestions.
Increasing reaction times. This can be practiced, while knowing your draw routine and being able to do it without error is something, learning to react quickly to the proper stimulus is important. I.E. Furtive movement.
Finding cover/concealment is great, but keeping an "eye" on your target is just as important. Knowing whether they are advancing, flanking, or retreating is vital.
Understand your opponents goals. Are they shooting defensively, offensively, or violently. To explain this, the defensive shooter wishes to leave, get away. The Offensive shooter has the intention to continue the fight, but still doesn't wish to die. The violent shooter doesn't care for themselves or you. I would change tactics based on the situation. This may already be covered but it sticks out in my mind.
Never use the same cover, position, timing, or tactic more than twice. By timing I mean waiting for them to stop firing before firing, and never doing that in the same place more than twice. An old teaching says just because it works the first two times, doesn't mean it will work a third.
Know the pros and cons of everything yo have to work with. The cons are more important. In other words, know how to defeat yourself to win against them. Not knowing your policies, defensive action is for me and most to be the objective, not seeking out and killing.
Your list seemed to be perfect as is, my mentions may just be a bit esoteric, but they are my thoughts.
"Today is victory over yourself of yesterday; tomorrow is your victory over lesser men." - Miyamoto Musashi
[Insert random irrelevant religious quote here]