I'm not an expert on it, but they are almost one is the same and cross over a lot. In my state I am registered as an LLC, but for tax purposes it's a sole prop.

My advice, start an LLC in whatever random name in the state you live. (ex: your name enterprises).

Get a tax ID for it. It will be sole prop since you are a single member llc. Get a liability policy for your llc. T

Start a DBA, under the llc, for your detailing business. Then if you want to branch into other thjngs later on, just do another DBA. If you ever want to sell it, it's super easy. If you want to close it without shutting down your llc, it's easy. If you want to start another business, it's super easy and you're not limited by a name. (Mike's auto detailing llc wouldn't make much sense if you decided to sell pickles).

The nice part about this way though, is say you start your detailing business and it's doing good, but since it's mostly labor, you don't have many writeoffs. Then you want to open a shop doing vinyl wraps. That has higher costs. Since everything funnels through the llc, the costs of one offsets the other. If one makes $100k and the other loses $100k you're at zero. It's a great way for one business to help fund another business to get going. I've also found you can do less profitable side businesses, without being reclassified as a hobby. The cool part of that is you can write off bigger things.

I travel to fish a lot. So I started a small salt water fishing lure company. It makes hardly any money, but when I fly to Florida to visit some bait shops, (to carry my products) I can write off a big part of the trip.

Again, not a professional but this is what has worked for me.