For me, mediumship "just happens". When I've helped others, it's common for a deceased loved one to be present to assist. Sometimes they give me information to give to the person I'm working on. Other times, they have shown me techniques/tools to help that person. I always loved the latter, as it adds a new tool to my toolbox.
More recently, I've focused on recognizing symbols that my loved ones leave for me. For example, I'll find a marble in a very uncanny area, that's my paternal grandmother reminding me to play and have fun. Her husband leaves ammo cartridges, or casings, to remind me that they see my efforts and work. My other grandmother leaves feathers, and my father leaves coins. There are plenty of times when I can just feel that one of them is near, and/or had influence on a situation, like leading me to a new client. I always thank them, usually out loud, because I know that helps them, and that they can hear/feel my gratitude.