how handle the problem of emotions, anxiety in a interview and how improve communicatiosn skills

Hi all,
i have two problem:
one is the common in any interview: how handle the problem of emotions, anxiety
one is the following: how improve the skill of comunications
For example:
when I have 4 people in front of me in an interview and they ask me a generic thing: as "tell me about the new ipo" although I have read and know the topic, many times I get lost and confused and I not express the topic clearly.
so I ask you how improve the ability to express a concept clearly, mastery of a situation where we are in trouble.
it is better to follow a pattern in mind or practicing before the interview?
Some methods (eg practice) can be useful when we know the topic, but for example when we do not know the answer you follow a pattern? which ? (problem, how to solve it, but this is very difficult when there are 4 people who are watching you)
In conclusion I would like to know how you manage this problem, how you improved this skills (as you have transformed your weakness (comunication skils) in your strength) and how you dealt these problems
Thank you
Alessio