How to start a business in california?

Hi. I am a female in my mid-30s who has been working for a water restoration company, but I only do inventory for them when needed, so I don't officially work for the boos, but whenever he needs me. To better explain what I do is this: You have a water flood/damage to your property and besides the dwelling, you might also have content coverage of let's say $100K and some or all of your contents were damaged and you need to write a long list of inventory for your insurance to later get compensated, but because your damage could be extensive, it is a tedious work, so when there is a need to do an inventory, the company boss would ask me to come to the property and document the damages so we could present it to the adjusters on behalf of the insured. Some people don't know how to do it and some find it annoying, so I would get paid a certain percentage of the amount I would bring to the insured. So I learned how to do that and I would like to work on my own on the side too, but I am not sure how to start my own such business or even if it would be possible as I don't even know what my work would be called lol. I want to get a few tips as to how to legally begin doing this myself? Are there any people who do this themselves? What could I be called? What baby steps to take? I never had a business so IM clueless?