1. Say "no" to toilet storage. Do not allow your husband to store old toilets in the backyard because "it's funny". OK, for 24 hours it was funny and then it was over.
2. Be agreeable within reason. Any renovation is challenging and you should expect to live without creature comforts for quite some time. However, just because the electrician says that there's no other way to move forward, do not agree to demolish the whole house and move into the litter box without consulting your husband first.
3. Throw more bodies at the job. Your incredibly smart, talented, curious husband may want to try his hand at every project, but it will take 30 years to renovate the whole house if he does it all by himself since he has a very full time job already. Do hire people.
4. Be kind to your mother. Do not tell her how much anything costs. It will freak her out. I learned this lesson long before we started this renovation. She will sleep better and so will you.
5. Be sensible. When your plumber roughs in the plumbing downstairs, make sure he/she caps off the sewer vents so that your entire house does not smell like a porta-potty.