Be friendly. Smile and look engaged. Try and chat to people for advice about how they got started. (But choose your moment - not when they're clearly preoccupied. Maybe ask if there's a time at the end of the day you could come back and speak to them for 5 mins.) Be present (ie don't be the person hovering by the door looking to shoot off as soon as you can.) If you're going to get/ make a coffee/ tea - ask if you can make it for anyone else.