​I have a really good idea that I know I’d enjoy doing as a side hustle… I just have no clue where to start!

Like how do I make my services known?? Do I make cards and just randomly give them out to people? Should I get a separate phone for the side hustle? Do I advertise using my vehicle? Should I start with family members, their friends/coworkers, my coworkers? Do I get an LLC?? Jesus idk. It’s just a side hustle so would an LLC even be necessary? How would my taxes work.. oh man..

I’m in school, should I just get some extra courses during summer for business and accounting?