If you know what your objective is with hiring an architect, then you should be able to ask the right questions relating to that goal. A question I usually start with is about their advice on design.
Before I get into execution, I like to know what their overall opinions are because they are experts and definitely know more than I do.
Secondly, once you get a clear picture of their vision for you, you can proceed to ask about the drawings themselves. 3D renditions, for example, are pretty great and you should ask if you’ll be getting that or not.
Another important thing an architect can help you with is obtaining planning permission. So feel free to ask questions about this topic too. You want to know whether or not you would even need a planning permission in the first place, and if they can help you with it.