Speak softly... and carry a big stick. In other words, be approachable and genial and make light friendly conversation on arrival...... but know your worth and don't feel intimidated. You are auditioning them as much as they are auditioning you.
Chat with the drummer and keep eye contact with him. You will be seen to be locking in, he will appreciate it.... and his could be the vote you need if it comes down to you and one other.
Let them know what other skills/useful things you bring to the table. e.g. are you great at listings, social media, have a following of your own, do you own a PA/van etc....
Good luck!