Always have a mirror holster available so you can carry on your weak side if necessary.
Next, if you find that you have eye dominance problems or need a two-handed survival shooting technique I have one that's simple.
Grip your pistol in a two-handed fashion in your weak hand. Rather than weaver or pull the firearm to your opposite eye, simply rotate at the wrists. You only need to rotate the pistol far enough to bring the sights in-line with your strong eye. Sight alignment fundamentals still apply, even if it's completely upside down. The slight rotation is enough to align the pistol with your eye, but not enough to give it the "what up dog" sideways look.
I've used this to help people with eye injuries and cross dominance issues at the same time to overcome their limitations and successfully shoot. It's now a technique that I suggest people learn. It's faster than trying to focus with the weak eye while having the brain say, "hey dummy, that's the wrong eye!"