My relationships have always started out with us being friends first, but I think we were pretty clear on when we were friends and when we were more than friends.
Would You Ever Consider a "Friends with Benefits" Relationship?
As a continuation, I tend to become fond of someone even before going out with them. No way I could sleep with someone and still consider them just a friend. Hugs, stuff like that, I do that with friends all the time, anything more though, and you better be pretty close to me, otherwise I'm liable to shut you out.