What are some important tips for CIOs and CTOs to be ready for the boardroom?

This is a very good question. My experience is that the questions were security protection (cyber attacks, virus protection, ransomware, etc), risk mitigation plans such as disaster recover testing and plans and your support to the business strategic plans/goals. Also audit findings in the IT area, how are you addressing, are the findings being closed timely,

bring in flavour of how top three leaders in your business space are successful and why....another angle would be highlight threats if not paid attention.
 

Create a Risk Management Document along with all areas involved, that has an action plan to be executed when risks arises.

Know your facts, don't get flustered, present everything in a business, not technical context