dba vs LLC

(Charlotte, NC)

I'm a certified personal trainer with liability insurance and I make all my clients sign waivers. I would like to register my business name before someone else takes the name and not sure where to start. Should I just do dba or do LLC? Its just me as a trainer and I do mobile personal training, I do not have a studio. I'm the only employee and its more of side job and hoping to be full time if I get enough clients. I travel to people's homes within 25 miles of where I live to provide personal training services.