Almost all the thespians you appreciate, are perfectionists – they rehearse so much, that at times the final shot that is canned is the one that is the 73rd Take (in movie making parlance). For a live 3 hour performance, Pt Ravi Shanker used to practice on his sitar for consecutive 6-8 such 3 hour sorties; the undrelying condition being NOT a single note had to go wrong on those sorties. Naturally, there was perfection in the ‘real’ performance.
So, if you are going for an interview, try to arrange a few Mocks. These clean your act, empower you, make your though fluid – validate your assumptions, or prompt you to improvise a few responses. Your thinking gets clearer.
Don’t overdo, lest the spontaneity is lost.
In a similar vein, one technique that truly helps is:
Ask yourself 5 questions, and answer them yourself.
This is indeed a great rehearsal.
Watching a videography of your mock reveals a thousand learnings. Watch these 2-3 tiimes at least.