Taking it slow

I'm 18 years old and I recently Started talking To this guy I met at work. Thing is he's 25. It started out simply, we started bumping into each other and teasing one another and then the flirting just progressed. Then one day after work we were alone in the break room and he started to get more touchy (which was fine by me) and he pulled me into an amazing spectacular kiss. Since then out text have been getting some sexual undertones and although I do want to go further with him I think it would be best to take it slow because I don't want to seem like an easy naive kid. Any advice on how to do this? He's been totally respectful about everything, asking where it was okay to put his hands. I just don't really know how to act around someone whose not a total horny little boy.