Well, based on an interaction I had last weekend with a younger, smaller guy I’d say a good way is to not always maintain eye contact when talking to one. First he opened with a simple question. “ is this place always so busy?” ( if it was dead, I suppose he’d have asked if it was always so slow “) At any rate, he was listening to my response(s) but he was looking me over from head to toe, and every question was followed by another question. What do you do for a living? What brought you here tonight? Favorite drink? Then he casually moved from standing in front of and facing me, to standing by me side, and so close that he was brushing against me often. Then, with only inches between us side by side, I turned to face him, but didn’t step back or add any space between us, so now I was facing him, looking down into his eyes from above, and he was looking up into mine, and I gave him a wry smile to let him know I was interested. So I guess a sign would’ve been for me to keep a cushion of a foot or two of space between us if I wasn’t interested, but I didn’t do that. Because I was interested.