During initial visit, the Reiki Practitioner will spend time, ask what you are there for, and collect some historical information regarding the specific issue. Once that has been established, you will lie on a massage table, fully clothed, and the practitioner will start by placing their hands on your head and slowly working their way towards your feet.
Here is a nice description on what to expect during a Reiki session in the article below; please check out the illustrations:
http://www.nyu.edu/classes/keefer/nature/Paule.html
Choosing a Reiki Practitioner is a personal and subjective process. Please note, Reiki therapy should always be considered supportive and complimentary to any standard medical treatment. While there are no state licensure requirements specific to Reiki, some states require Reiki practitioners to be licensed as Massage Therapists to practice Reiki. You can look at their education, experience or certification level, however, ultimately trust yourself and choose the practitioner you feel most comfortable with!