It's no secret, for guys at least, that a firm handshake administered while looking the shakee directly in the eye is a big deal. I'd add that frequency matters a lot, too. I started to say, "While I'm no politician ..." But of course I am. Anyone aiming to bring about change is a politician by definition. (It's just that some deny it—the word for them is "clueless.") Back to frequency: I purposefully reach out (literally) to shake as many hands as possible—and often a couple of times. I find it makes a big difference. ("Shake your way to success"?) (Is this as big a deal for women?? Regardless of gender, limp-sweaty handshakes are, um, not very good advertisements. Don't bother reminding me that "crusher handshakes" are just as bad—I agree without prompting.)
More Body Language. It's a commonplace observation that folding your arms in front of you is a "put-off" gesture. (Big time.) A friend who, among other things, works on customer friendliness in hospitals, Dr Thom Mayer, really whacks on Docs for folding their arms in front of them while addressing patients. Well, believe it or not, I have a deep-seated shyness streak. (No joke. A lot of good "stage performers" do.) And I often find myself hiding behind folded arms; so much so that it's physically difficult for me to unfold, even around friends. After re-reading a body language book I was asked to endorse (and did endorse), I renewed my commitment to become more conscious of this wretched gesture. In the short term my conscious reminders are helping a bit. I urge you to tread the same path.
Bottom bottom line: Body Language matters. A lot. Employee entrances (corporate body language). Hand shakes. Folded arms. Et cetera.