What should I do?!? Help!!!?

This saturday me and my boyfriend are going to a creek just to hang out and be together. Thing is my dad is going to take us and the creek is right by my grandmothers house. I don`t know what to wear or what to talk about in the car with my dad. I love him with all my heart and Im dying to kiss him. Any tips???????? How to I go for it? Its not like I haven't kissed before its just my past boyfriends didn't mean as much as he does to me. So this time I really want it to be perfect.