[Felix The Assassin]

That is your own personal Stress Alert System 'fight or flight' engaging.
A start has already begun, you have indentified it, and asscoiated it with your discomfort in public, or within an unknown environment.
You are not alone in this, a lot of young folks seem to have this now.
The itchy feeling in your throat is spot on, you have subconcisely dried your throat, and you are now straining too "wet your whistle" whilst attempting to carry on. After the event, and your body returns to normal, your thorax is back to normal as well.
At work, for new instructor certification, repitition is the key to success in the program. A lot of them have very limited experience presenting information in a formal class environment. It's just a little different than barking ordes to 25+ soldiers in captive audience formation type setting.
Eye contact. From an instructors point of view. If presented with an auditorium of 235 or a small class of 8, I attempt to make direct contatc with everyone at least once.
If in a casual environment, occasional eye contact should be made with everybody that is present.

Now, get off the internet and go find somebody new to converse with!