Before you launch the big plan, find one person whose job is to poke holes in it. Then thank them.

Plans built inside your own head inherit your blind spots, and the people close to you are often too kind to name them. Appointing somebody specifically to look for problems removes the awkwardness, because objecting is now the job rather than an act of disloyalty. Finding the holes beforehand costs an afternoon. Finding them afterwards costs the plan.

Ask one person who is sharp and not especially gentle to tell you what is wrong with your idea, and ask for three things. Write them down without defending yourself. Then thank them properly, since you will want them to do it again.