I remember way back when I got my first reading, years before I decided to take the journey to become a professional. I was really nervous! I had a lot of butterflies, I didn't know what to expect or what they were going to say.
Years later, from the perspective of a psychic reader, the best advice that I can tell you in preparing for a reading is to enter into the experience as calm and relaxed as possible. Be ready to receive. You may still have butterflies like I did, try to simply acknowledge them and let them go.
It is a good idea to keep any specific questions that you have written down on a piece of paper, just to keep yourself focused, but also know that readings are all unique experiences in time. Spirit will always communicate with us exactly what we need to know in the present. Sometimes this is information radically different than what we were expecting to hear or discuss!
After a reading, it's also advisable to have some quiet time and downtime to process. Be sure to stay hydrated and get plenty of rest in the following 24 hours.