I try to get some information over the phone and then set up an on-site inspection. At this appointment I talk with the customer about what they are trying to achieve. I usually email the completed estimate the same day.
Primarily residential. I do have some experience working with apartment complexes as well.
Know what your goals and budget are ahead of time. Look for someone trustworthy who is not going to hide anything from you and who is going to begin and complete the job efficiently.