File Sch C with an occupation like Entertainment.   Report income and ordinary and necessary business expenses.  You pay self-employment taxes at twice the rate of an employee for social security.  In 2019 will probably benefit from the 20% pass-through reduction in income for income tax but will not reduce self-employment tax (same as FICA if an employee).  

There are individuals tax preparers who will work with you  
Try googling “tax preparation for escorts”. You’ll be surprised at the results. Make sure to get references when you choose a preparer.  

Willful failure to file is a felony, and gross under reporting of income (>25% diffference between what you actually reported and what you should have reported) extends the statute of limitations to 6 years instead of 3. So, yes, file tax returns, especially if a) this is your only source of income or b) it’s not your only source, but it’s a big enough source to allow for changes in lifestyle.  

Filing taxes is super smart. Especially if this is your only source of income. Not just to keep the change of lifestyle/affording lifestyle questions at bay but also for purchasing a home, cars, etc. There are many sex worker friendly accountants. Mine is a super religious mormon guy who is prominent in his community. We share some laughs over his "side business".

But isn't a tax preparer who receives a fee from a provider violating ARS 13-3204?  Or at least this would be probable cause if a tax preparer charges a fee to a provider to file her taxes, by receiving money from her?  

Not likely, as you start to get into violations of rights and privacy and attorney-client or accountant-client privilege.

There is no such thing as accountant-client privilege only for an attorney or doctor.

In fact, privilege is not limited to attorneys and doctors. There are several privileges including the marital privilege and priest-penitent privilege. And when it comes to numbers on the tax return, there is no attorney-client privilege.