Do you have any advice you can offer someone writing a business plan for the first time?

We're giving ourself 1 full month to actually write it so we aren't rushing.
I hope that is enough time.

I'm just wondering if there is anything you found out after you wrote your plan that you wish you knew while writing it?

We're in the process of trying to start our own reptile store. I'm sick of seeing people purchase reptiles from pet stores that know nothing about them.

My goal is to sell only quality captive bred reptiles.

Anyway.. any advice you can give I'd appreciate.