Staff need to be classified correctly as either a contractor or an employee. Contractors need particular attention, as you need to consider when a contractor can be regarded as a common law employee.
If a contractor is regarded as such, you may be liable for Super, Workers Compensation, Payroll Tax and Leave entitlements.
Generally, if a contractor has their own business entity and works for multiple businesses (not just your practice), they will likely meet the classification as a contractor.