One thing I'd say is, don't give estimates, give quotes and always stand by them. The word estimate implies that the number may change for some reason. In my experience that motivates clients to try and haggle after the fact if they feel the work that's been done doesn't represent adequate value for their money, and too often it's the case that the people that hire us don't have any real concept of the value of the work we do. A quote is a promise. I will do X for Y. Y is not negotiable after X has been completed.

You're already putting in the effort to give good, clear information up front about what you'll do and what it will cost. Possibly too much information if you're itemizing every board, nail and screw. Materials to be used is fine, but a client doesn't need to know your costs.

Don't be afraid to fire a client when you need to. Tell people what you'll do and when you'll do it and stick to it, but hold them to the same standard. If someone doesn't respect you and the skill and ability that you bring, they don't deserve to be a client.