You will need to find out some basic information about how your board operates.  Some of this information can be found online at the board website and especially in the Trustee Code of Conduct:

• How many trustees are there in your board?
• When and how often does your board meet?  Are the meetings live-streamed? Consult the meetings page on the board website. 
• Where are the meeting agendas/minutes located on the website?
• What were the major issues discussed during the previous term of the board?
• Where can you find the board's multi-year strategic plan? You should read it and decide whether you support or oppose the various parts of the plan and develop talking points for them.
• What are the Rules of Order used by the board to conduct board meetings?
• Where can I find my board's Trustee Code of Conduct to find out guidelines on civil behaviour, whether you can accept gifts, in what circumstances you can comp a guest's meals (called Hospitality), etc.?
• Where can I read the Education Act and Regulations?
• Where do I find the Municipal Freedom of Information and Protection of Privacy Act and Regulations?
• Where can I read the Municipal Conflict of Interest Act?
• Where are the Board's By-Laws and Policies?

For other topics, you'll need to dig deeper by asking someone knowledgable about the board, such as a sitting trustee or someone very knowledgable about the board.

Basic questions you should ask are:

• How many meetings are you required to attend? How many subcommittee meetings will you have to participate in?
• What is the time commitment for being a trustee?
• What is the honorarium paid to trustees?
• What is the trustee's expense budget limit and what type of costs may be recouped?
• How long have each of the incumbents been serving as trustee?
• Are there any trustees who are not running again or any vacant seats?