I am surprised that no one has mentioned pay by billable hour yet. (Unless I just missed it in my admittedly cursory scan).
Be wary of advertised "per hour" rates. Many times (especially outpatient pediatrics and homehealth) facilities mention that they will pay $X per hour, but they don't mention that it is for each billable hour only. This does not account for driving time or documentation time. In a normal 8 hour day, it is difficult to stack 8 billable patient hours. So even if these postings talk about $80 an hour, you aren't actually making that much.
Also, if your patients/clients cancel, you will not be paid for that hour since you cannot bill a session. (Keep in mind that this will affect how you budget, especially during holiday times or summer vacations for pediatrics).
I live in SoCal, and this is something that was common during job searching. If you wanted to negotiate a salary (so you get paid even if patients cancel), they usually offer one at a significantly reduced rate. One early intervention site I interviewed with offered $45 an hour for billable hours, but only a $65,000 salary if I wanted a steady paycheck. And they definitely have productivity requirements to go with that salary.