What does her business plan look like? That’s the first place to start.
She’ll want to have a good idea of how many clients she (and whatever staff she hires) can service in a normal day – not just “capacity”, as in “how many can we possibly fit in?” but realistic: “how many customers are we likely to have in a day, a week, a month?” That will help her to get an idea of how much she will need to charge to break even (balanced against other aspects of the business plan: expenses for rent, utilities, taxes unrelated to income, maintenance and improvement set-asides, capital costs and debt service, etc. as well as her own salary, staff and custodial people, etc. How will she advertise and what will that cost? That needs to be in the plan, too.
Then as a sort of sanity check she should check out her competition, meaning all other beauty salons (including “beauty academies” who offer similar services at lower rates) in the geographical area she expects to serve. That is, she should know what services are offered, the quality and time of delivery and rough-to-precise ideas about cost (and if possible, satisfaction level of the competitors’ customer base). This will give her some real data to check her expected income against, and help her in setting prices.
It would also be a good idea to discuss her general idea with someone at the local Chamber of Commerce, who may be able to give her valuable advice as to specific regulatory quirks that even lawyers may not know, since they don’t often have to deal with bureaucratic regulation. C of C people are up against that stuff all the time.