Many architecture institutes from around the world offer guidance to the consumer in relation to engaging an architect. From a quick google, for example, questions proposed by the American Institute of Architects
20 Questions to Ask An Architect
Your architect should be able to provide detailed answers to each of the following questions. Remember! Your comfort and convenience, not to mention your budget and design goals, are the highest priority, so be sure to interview more than one architect before making your decision.
1. What does the architect see as important issues or considerations in your project? What are the challenges of the project?
2. How will the architect approach your project?
3. How will the architect gather information about your needs, goals, etc.?
4. How will the architect establish priorities and make decisions?
5. Who from the architecture firm will you be dealing with directly? Is it the same person who will be designing the project? Who will be designing your project?
6. How interested is the architect in this project?
7. How busy is the architect?
8. What are the steps in the design process?
9. How does the architect organize the process?
10. What does the architect expect you to provide?
11. What is the architect's design philosophy?
12. What is the architect's experience/track record with cost estimating?
13. What will the architect show you along the way to explain the project? Will you see drawings or sketches?
14. What services does the architect provide during construction?
15. How disruptive will construction be? How long does the architect expect it to take to complete your project?
16. What sets this architect apart from the rest?
17. How does the architect establish fees?
18. What would the architect expect the fee to be for this project?
19. If the scope of the project changes, how will additional fees be determined?
20. Do you have a list of past clients that the architect has worked with?
There is further useful advice in the RIAI consumer section in relation to engaging a registered architect etc.
Best of luck!