First thing you got to do is make a list of service providers from yellow pages, newspaper advertisements and through internet. Now browse through them and choose the one who will suit you, now discuss about them with your friends and relatives and know about their experience, service and efficiency. Now take steps to meet them and find out their nearest locality and what the formalities are to meet your requirements.
Prepare questions about their method of treatment, their qualification and existence period. Also check if they have proper approval from government and possess a legal insurance. Make sure they have modern equipment and charge a considerable pay. After all these consideration if you are satisfied then you sign an agreement with them.