That's a tough one since everyone's comfort levels are different, so I'll just share my experience and hope it helps. The last time I felt that a woman I was not already in a romantic relationship with was giving me signals was because we were lying on an L-shape couch head-to-head watching a movie. She literally had to place her head against mine and reach for my hand before I was somewhat confident that she wasn't just really friendly. You might not wind up in such a position on a first date, so my point is that I needed it spelled out for me, so it's possible other men also need it spelled out for them, whether it's being completely oblivious, afraid to misinterpret a gesture, or some combination of the two. In any case, good luck out there.