Whole lot a shakin' going on
-The bone crusher. A surprising number of females go for the extra-firm, which comes across as over-compensating. The crusher is usually a male macho thing, though, which reads as though yes you are very strong, a very strong knuckle-dragging Neanderthal.
-The clammyhand. Easily the most disgusting of handshakes, as who wants to grip a sweaty hand? If you are susceptible to wet palms, wash beforehand, keep your hand open and exposed, and a surreptitious wipe before the clasp is advised. The sweathog is the kiss of death of first impressions.
-The iconoclasp. This is anything other than the traditional handshake and there are a lot of subcategories. I've never encountered this in an interview, but it does come up a lot in social situations. Unlike the choreographed hand-dances and gleeful fist-bangers that you sometimes see, or even the thankfully passe handslaps (where one pleads for the geeky high-five, gimme-five, down-low or whatever, and the other mercifully cooperates to minimize the embarrassment), there is occasionally some confusion between the traditional and the I-love-you-man-clasp (interlocking thumbs, palms on back of hands like a wristwrestling grip). Usually this is avoided by carefully observing the position of the offered hand. Straighthand at 90 degrees, you've got yourself a traditional; slightly cupped hand at somewhere between 90 and 45 degrees, an I-love-you-man is on the way. But occasionally the angle is too close to horizontal or the up-angle not perceived, or worse yet the straighthand is offered but grabbed with the I-love-you-man (or vice-versa) and the awkwardness ensues. It's kind of like that first kiss situation. You're expecting the right tilt lip kiss, from which you can adjust to the situation as needed, but the initial left tilt, cheek peck, or open-mouth can throw you off.
-The two hander. Usually a topper hand, sometimes a forearm touch, and rarely a shoulder slap, the left hand is intended to convey warmth, but it is risky. When pulled off successfully, it can be genius, but the attempt is fraught with peril and easily overplayed.
-The pumper (or the rare variation, the pull and pump). A common rookie mistake in which the handshake is too vigorous and often prolonged to the point of awkwardness. It's possible to pull this off if engaged in hearty banter, but better to pull out before it's too late.
-The offhander. If there isn't a medical reason for using the left handed shake, you ain't gettin' the job.
-The fourfinger. This could refer to all off-grips, but except for the rare overgrip, you never really see any other off-centers except for the fourfinger, which is all too common. This occurs when the grabber comes up short of the proper thumb lock position, often due to a premature squeeze, and is left with only a hand full of fingers. I really hate this truncated shake, and while most people will go through with the shortshake, I will generally call for a reshake, which is acceptable under these circumstances.
I just deleted a couple of paragraphs on the "proper" handshake, as they were pretty boring and you can read that stuff elsewhere. Instead:
"In a new study, scientists put 98 students through mock job interviews with businesspeople. The students also met with trained handshake raters who, unbeknownst to the students, rated their grips. Separately, the businesspeople graded each student's overall performance and hireability. The two group's scores were then compared.
Students who got high handshake marks were also rated most hireable.
'We've always heard that interviewers make up their mind about a person in the first two or three minutes of an interview, no matter how long the interview lasts,' said study leader Greg Stewart, associate professor of management and organizations at the University of Iowa. 'We found that the first impression begins with a handshake that sets the tone for the rest of the interview.'
The study [was] detailed in September in the Journal of Applied Psychology. " (http://www.livescience.com/health/080507-firm-handshake.html)