I'm sure you already know that to become a dermatologist you will have to complete 12 years of post-secondary education/training - four years in a bachelor's degree program, four years of medical school and four years in a residency. All of this experience will help you determine if you want to start your own practice, and what will be needed to set yourself up for success.
I found this interesting and very specific website for those who want to start their own dermatology practice: https://www.modmed.com/newderms/. Check it out to learn all the different facets of starting your own medical business. I wish you all the best!