I have been a medium for as far back as I remember. As a matter of fact I think I do my best work with some incense ,a candle and my client. Many people I know who do this kind of work have different ways they prepare for it. I am kind of fussy when It comes to mediumship. I have certain things I go by.
First of all I like to do my work out of my home. I have my home cleared and it is the space I am most comfortable in. I always prepare for a session. I meditate,clear space,protect myself and call in my guides.I know I can trust them to bring through spirit that needs to be heard.
Most importantly a medium needs to trust and believe in themselves. Know that the messages you are receiving are coming through for a reason. Nothing is to ridiculous (even if it seems so)to pass on. If you do this type of work,sit back breathe and let the information flow !