After you have selected a designer, you should prepare the following.
Whether it’s the low priced or the high priced firm. The low guy will most likely not give you the best set of plans. Remember you can not pay a little and get a lot but sometimes you can pay a lot and get a little. The high priced firm might not give the best value for your money. You might be paying for name recognition.
Take note on how many sheets and how detailed the plans are and mentally compare between 2 or 3 other firms. Are the plans neat and readable? Do the plans have enough wall sections and details? Plans that do not have sufficient details will cost you money during construction.
Contact both individuals and general contractors that have worked with the firm in the past. Ask them if there were any problems with the plans and if they would work with them again.