In no particular order, here are some key things to look for as you select a design professional for your renovation project. You should decide on the relative priority of these issues before interviewing designers.
Fees for professional design services have a huge range. The methods of determining fees usually fall into two main groups: percentage of construction cost and hourly. Designers whose fees are figured as a percentage of construction cost will typically fall in the 5% to 8% range. The problem with this type of fee structure is that there is a small, though not insignificant disincentive for the designer to promote cost effective design solutions. Though the architect will bill progressively through the project, it is unlikely that there will be a "refund" at the end of construction.
The hourly rate structure, however, provides little incentive for the architect to complete the drawings in a timely manner. A good compromise is the "hourly-not-to-exceed" rate structure. The architect estimates the amount of time it will take to complete the drawings and provides the client with a "cap" on the fees. This way the client has a good sense of how much design will cost, and is still protected from unexpected design fees.
A few design professionals who have significant experience in renovation projects will bid by the square foot.