I have to try the looking in the eye thing. I have a feeling it would freak my wife out...I can't often look people in the eyes when I speak to them, during sex, this might be even stranger...What happens if one person bursts out laughing? :-)
I couldn't look people in the eyes, either, until I was in my early 20's. For me, it was a confidence thing. Not that I had NONE, just that I felt overly conscious about it.
I was like that until somebody pointed it out to me, and I decided then and there that I'd make the effort to change, and I did.
A good trick that somebody told me is to look at the space between somebody's eyes when you're talking to them. This avoids your own eyes going back and forth, or making you look c0ck-eyed.
It was surprisingly easy to do, and I noticed very quickly that people were more comfortable with me in general, not just in speaking with me. Now I TOTALLY notice when somebody doesn't look me in the eyes when speaking, and I find it terribly awkward.
I also had a very limp handshake (which, as a man, is noticeable). At the same time, I made the effort to give a firm handshake, and the difference it made was noticeable, as well. It commands a certain respect, both things, and people tend to react accordingly. Just don't over-do either. As a smaller man (I'm 5'7"), you're already at a certain disadvantage before you even open your mouth, meaning that most people have already started to judge you. Small, quiet and shy = weak. Small, loud and brash = over-compensating. The trick is to balance every thing.
The worst, though, is the people who look you up and down while speaking to you. Hate that. And those that try to rip your arm off when they shake your hand.