The importance of schmoozing can hardly be underestimated, and it hardly ever is.
The true questions are when, how, and to whom to schmooze.
WHEN: Always schmooze. There is no inappropriate time. For men, one of the best times is when you happen to meet your schmoozee at a lavatory urinal. This is ideal, because obviously the schmoozee cannot make too hasty an exit. He is, as it were, all ears (he certainly won't let his eyes wander).
HOW: Introduce yourself, giving your name and your academic affiliation. If you have ever seen the schmoozee before, mention it (e.g.: "Professor Whitehead, nice to see you. My name is Chris Nagel, from Duquesne University. I saw you catching a bus once, in February of 1937"). Mention any publication of the schmoozee that you have read -- in case the schmoozee asks about it --, regardless of its importance. Also, in mentioning the schmoozee's published work, be sure to indicate how it has advanced your own (e.g.: "I read your limerick about the man from Nantucket in the middle toilet stall the other day. It has made a big difference in how I interpret ideal essences!"). Finally, end your conversation with an open-ended allusion to a deeper, continued relationship; however, be cautious not to appear too subservient or obsequious.
DO: "We should discuss this in more depth later. Enjoy the session on 'Evidentiary Ethical Postulates and Undecidability in Relation to Really Uninteresting Stuff'!"
DON'T: "I'm in room 1409. If you'd like, tonight, if you're feeling... lonely... you could come up. Any time. I'll be there... alone... all night."
TO WHOM: Appropriate schmoozing depends on your own academic position more than the schmoozee's. Say you are a graduate student Ph.D. candidate at a second tier (at best) private, Catholic university east of the Mississippi that is not named "Loyola." From this vantage point, everyone is good to schmooze (e.g.: "Say, you work for the custodial crew of the hotel, don't you? I just wanted to tell you that your interpretation of vacuuming and emptying ash-trays has genuinely helped me understand Sartre's third ekstasis of being for-self. I was wondering if you could score me one of those leftover boxes of Zinfandel").