So after a date or two when the guy knows the girl likes him he takes her her home and says "I had a good time with you tonight." He then touches his forehead against her and sees how she reacts, if she stands still for a few and does not back away as they look into each others eyes he knows he can kiss her.
It is good, never just jump in (bloody nose may result lol) ... But, even if she turns away it doesn't necessarily mean she doesn't want to.. In my case, nerves always get in the way his first couple attempts and I end up turning and laughing awkwardly - I'm good for the kiss just panic when I get nervous - which is why slow is always safer haha - usually you can tell the difference tho!