I'll give this one a quick shove back on topic.
For me kissing is definitely the most intimate part of hooking up with someone - if they're good at kissing it makes all the rest of the session so much better, but on the flip side an awful kisser can make it all a bit less fun.
Second would probably be fingering - there's something about having someone lying alongside me (with all the body contact...and kissing) with their fingers busy in unmentionable places that really does it for me.