The number one thing I've found is best to present when interviewing for any job, is enthusiasm. Someone who gets genuinely excited about their work will absolutely stand out from someone who is just doing it for a paycheck.
Whenever I interview people (I'm an electrical engineer), my recommendations are always for the candidates who have a lab at home, or tinker around at home... someone who has a passion for the field.
Make sure you've got all the requirements met (personability, technical knowledge, etc.), but it's the passion for the job that will push you over the top.