You should meet with prospective architects to discuss the project and your requirements in detail, view their portfolios, and obtain contactable references. They should then advise you how they work and how they would proceed on the project.
Depending on the nature of the project, the working relationship can extend over several years, and it’s important that both parties feel comfortable.
If you wish to appoint them, and they’re willing to accept the appointment, first agree to the structure of fees. Then ask to complete the standard Client/Architect Agreement (for private sector use), as recommended by the South African Institute of Architects. It’s a legally binding document which clearly outlines the role and responsibilities of both parties.