Worker must devote substantially full time to the firm's business. To the extent work is performed on the firm's premises, this suggests control over the worker by the firm, especially if the work could be performed elsewhere. Firm requires the worker to submit regular reports to the firm. Periodic payments tend to indicate an employer-employee relationship. Firm is responsible for the worker's business and travel expenses.
Firm provides tools and materials necessary to complete the work.
If the worker has undertaken investments in facilities used to perform the services, this would tend to indicate that the worker is not an employee of the firm.