I suffer from PTSD. Some may call me paranoid but I would rather be called that than be called dead.
It is not always possible to pick the table where you want to sit but I make sure that where ever I have a commanding view of the restaurant. My first choice is to have a wall behind me or somewhere where it is impossible for someone to enter without me seeing them. Force of habit, I "case" the other people in the restaurant before being seated at a table. If I don't like what I see, I ask for another table and don't mind waiting.
I am far-sighted and sit within the last two to three rows of the movie theater but I always arrive early so I can sit in the middle so I have access to both entry doors and the two emergency exits.
And just in case you're wondering, I never leave my house without a gun attached to my body. I can't cover every contingency but I do my best. And my good buddy is a retired cop and our wives are good friends so we dine out a lot together. We cover each others back and at some places, even discuss a plan in the event something should go horribly wrong.
May the Schwartz Be With You.