Hello
I was looking for some information on "Platform Mediumship" and when I Googled it I came to find a older link to a thread here. So in the interest of what others might too come to find is they click the link like I did, I though I would share some thoughts on the topic.
As a Medium this work is something I have done solo and with others, what I note is that we all have "our way" of doing this work, and some of us stand very much present with the audience, some sit in more a trace state, some work in a team or with a partner. It all comes down to your comfort levels and how you can ground your energy.
So what is Platform work ? Below is a general outline, what a true event never should be is that "Side Show" as it is not a game and it is not something you play with or take lightly. Like the land of the living there are good and not so good forces that can come to you.
For some doing this work there is preparations done, meditation, grounding, being alone before the event, working with someone that can ground them and keep them protected. Some will surround themselves in a circle or have items of protection around them. Others like me get up there and are ready to go.
At times some will make their presence know to me days before the event and I will make note of their messages. You do not know whom might come in, and there can be some come in that do not have someone in the audience. What the Medium does is pick up the energy from the living person and from the dead person and link them together. We all have a vibration to us and family has a stronger one. We rely on our Guides to filter on some levels whom is there in spirit be a good fit with someone in your audience.
What can happen (though its rare) you can have an Earth Bound Spirit come to you this is one that is seeking at times that understanding and help with a "crossing to the Light" or some reason they missed that portal in dying. In this place I have two choices I can take the time there and then to do it, or I can ask my Guides to hold their energy for me til I can get there. Most times its an easy open the door and off they go.
Explaining to the audience what your going to do, and many times you can have that audience share in that experience with you with their energy. Making sure they know and understand the process and what they might even see. At times the audience will see a presence or energy around the Medium. This too you make your audience well aware of.
Before the event it is KEY to make sure that you ground and clear the energy space. That you call in the Divine and your Guides to be present not only to keep you safe and more importantly keep your audience safe. Your role is to keep things safe.
Rare on rare occasions you have someone from the audience bring in something dark with them, or you have someone that is there to try and throw you off your game as they do not believe. In this you have to be strong willed but too polite in how you react. Large events usually have "hired security" present to remove hecklers.
At times these events have more than one presenter on the same venue and you have to be open to working with others present that might or might not share your views on how it works. For me this is not an issue, where most have done a path of study or workshops or even work it for a living, I do not. Some will look at me at an event and go I do not know you......but they can read energy and know that I am as real as them. We all choose the path we walk with what we put out to the World.
After an event usually there is a bit of a meet and greet session, here too you never know what might come to you. Some Mediums are done and exhausted after, other's sadly at times I have found rush to the booze....to shut down. I know many that have had drinking issues. For me its a day in my life.
I hope that this personal view helps bridge some understandings in what one might see at an event or in a spiritual church and embrace that no two will likely present the same way.
Delivering messages from a platform enables Spirit to communicate with a larger audience.What happens during a demonstration of mediumship?A medium will stand on the platform and relay messages to the audience that they are receiving from the spirit world. Nothing frightening will happen, and contrary to popular belief, public services are never held in the dark.What is at times held in the dark is a séance or seance is an attempt to communicate with spirits. It is used specifically for a meeting of people who are gathered to receive messages from ghosts or to listen to a spirit medium discourse with or relay messages from spirits. For me I find this more a “Parlor Game”,
finding that believers and non-skeptics, treat it as a form of non-fictional science and spiritual reality.Mediumship can be a wonderful thing, giving people comfort in the knowledge that the existence of the human spirit is continuous beyond death.Lynn 
It was sad how Joanie slipped away but over the past dozen years similar things have happened to a lot of my friends. :( 