I consider only #2 as part of mindset, #1 & 3 are training/practice issues.
Number 2 is obtained by acquiring and maintaining a mental attitude (mindset) that you will do whatever is necessary to protect you and yours and other actions dictated by your moral position. I am not sure how you do that, other than just do it. It is not a task that all can achieve.
Number 1 comes from training from SD (gun or MA) schools and followup practice and, if possible experience.
Number 3 comes from learning the elements of awareness and practcing them.
A primary method of training and improvement of # 1 & 3 is experience, but that is hard to come by outside the military or LE.