Awesome question Englishguy! It's a difficult situation. As a guy, it is very easy to get into the "mood" and then get carried away. I think an important thing to do is to make sure that you do not get to the point where you focus on the physical. If you can kiss your girl out of a love for her (not a lust for her), you're probably alright. I believe it's a personal answer that you have to decide on your own.
One way you could look at it is like this: Only do what you would be okay with being your Facebook status. If you wouldn't mind all of your FB friends and family see that you kissed, then it's probably alright. However, if you would have to post something that grandma (or mom) wouldn't like, then it's probably not something you should do.