Introverts need time to prepare for the issues to be discussed. In an ideal case you should give them the agenda in advance so that they can fully participate in the discussion. If this is not possible, give them sone time after the discussion to think about further options and come with suggestions.
Provide quiet work environment
Too much external stimuli disturb introverts more than others. Therefore, if they can't work in a quiet place all the time, provide them with at least some space where they can think without any strong audio and visual intrusions. Let them work independently.
Hold meetings before lunch
Generally, introverts have the most energy in the morning when they are not overwhelmed by various external stimuli yet. Take advantage of this when organizing meetings.
Let introverts speak
Actively ask introverts to express their opinions and don't interrupt their speech. A moment of silence is not a problem. Make sure that extroverts will not start talking.
Communicate privately
Don't expect introverts to talk about their ideas spontaneously before a larger number of people. Bet on face-to-face conversations. If they are to speak at a meeting, inform them about it in advance.
-kk-