One of my favorite quotes from the Godfather trillogy is when Michael Corleone wisly reminds Vinnie, “never let anyone know what you are thinking.”
The importance of this is astronomical in client meetings. Never bring new ideas to the table in a client meeting. Bring vetted ideas. Prepare yourself before the meeting. Have concept sessions with colleagues, visualize the ideas, make sure you have the resources and be sure the idea is possible. When it comes time to present save a few in your back pocket just in case you need some amo.
If the client latches on to a “new idea” then you take the risk of have to execute it. If you realize later that it’s not possible or a weak idea, too late. Concepting is your job not the clients. If you transfer this power their understanding of their role will forever be jaded. This can cause a world of pain for you and them.