Anything I need to know when meeting my girlfriend's dad?

Today I am meeting my girlfriend’s dad in person. I wasn’t nervous at all but I am a bit now. I just want to make a good impression and I would like to know how I can overcome this nervousness. I am sure I will get over it once I am comfortable being around him, but if any of you guys have any experiences you want to share, how you faced your girlfriend or boyfriend’s dad, I would love to hear about them. I know I should just be myself, and you would be surprised me and her dad have some things in common so it shouldn’t be too hard, but what are things I can do to make a good impression?