Any suggestion?

I'm not sure is there is any book can be an instant remedy. I mean vocabulary and gramma cannot improve in several days. But here is some suggestion that might be helpful to you for effecitve meetings:

- What ever language you use, keep yourself clear-minded. Be organized before deliver any view point or comment. Always deliver one point at a time.

- Don't confuse yourself with complicated wording or sentence. Most regular words are already enough to express common topics in a meeting. Keep your sentence simple and short. it will help you to easily express your point and help the others understand you.

- pay attention to other people especially when they use special terms. This will be your "language" for the meeting..