Three simple improvements that you can make to yourself are to dress well, display good body language and listen. Dress not for the position in which you are applying, but for the position overseeing that one you applied for. A great outfit will give you confidence in yourself and naturally help you with your body language.
Carry yourself well and stand and sit with poise. 65% of communication is nonverbal; make your body language work for you.  Stand up straight, smile and remain confident throughout the interview.
Listen intently to the interviewer. Understand what is said before you respond. In an interview it is important to listen intently, comprehend fully and respond accordingly. If a question is confusing, reiterate what you understand to be said and ask for more clarification before you respond. Take your time to prepare your answers.
These three tips will make sure you stand out during your next interview.