When you are the table topics master…

Before starting the table topics session, briefly explain the purpose of
table topics.
When the meeting starts, look around the room and see if there are any
members who have no roles (called “silent members”). They are the best
candidates for the table topics questions. If you do not know their
names, do not hesitate to ask them!
If there are no such members, guests from other Toastmasters Clubs
with no roles come next.
When asking Toastmaster members to speak, ask different questions per
person – this is to ensure fairness at the voting time by allowing the
same length of time for each speaker before they speak.

If all the Toastmasters have roles, non-TM guests can be candidates, but
please check their confidence level and assign them with care.
In this case, the Table Topics Master can ask the same question as the
previous one to a non-Toastmaster –to make him/her feel comfortable.
At any time, avoid topics that questions political belief, religions, sexual
orientation or any other controversial issues.
It is recommended that you ask open questions, especially the ones that
include “what”, “how” or “why”, instead of a closed question (yes-no
question). That will help the speaker expand the contents of speech.