Great advice so far, but let's leave the audience alone for a moment and refocus back on the performer.
Mentalism is charismatic. Magic is as well, as is all performing, but very often a mental effect is heightened by the ability of the performer to catch, hold, and manipulate his or her audience. Therefore, I think that it is important that you reevaluate your performance character.
We are all unique individuals, but we must take those "real" aspects and amplify them to create our stage persona. What is it about you and your life experience that is interesting? Have you been a lawyer? Did you work in the Merchant Marine? Did you grow up in an interesting neighborhood? There are always parts of lives that are defining and that give us a unique worldview. How many times have you known someone who, at first glance, seems rather boring or uninteresting, and then you are thrust into an extended communication with this person, during which you learn a little more about them. Then, as you walk away, you think to yourself, "Wow, that person is pretty interesting. I never knew those things about them." You've gained a newborn respect for them. Why? Because they let you into their lives a little and you learned about what makes them unique and special. Mentalist need to do this all the time or else their act seems incredibly narcissistic.
Mentalism, I think, requires that you connect with people on a more intimate (real or imagined) level. I don't mean telling them the story of your divorce, but I do mean letting them into your worldview, letting them experience how you think and how you see things. That's what audiences will relate to. And then when you show them how this worldview frames and makes posible mysterious events (i.e. the tricks) then you've captured them--then they have something to hang their hat on.
Personally, I am uncomfortable with the 24/7 mentalist lifestyle, seeing myself as a "performer" of mysteries, and not one myself. But just think of the last person you met who absolutely captivated you with their conversation, their viewpoints, and their vision. Was it the INFORMATION that held your interest, or was it the person; their energy, their wit, their wisdom, or their quirky viewpoint?
Most likely it was all of the above. Take out the word "information" in that sentence and insert "mental effects" and you'll see the point I'm driving at.
I urge you to find a character that is active, not passive; engaging, not manic; accessible, not overly-mysterious. These paths have been taken 100's of times by mentalists the world over. For the trail-blazers in our craft, it's great. They were the first to carve out that niche. However, don't fall into the trap Magicians so often do--mimicing. In the 70s, how many Doug Henning clones were there? 80s, David Copperfield imitators? Today, Blaines?
On the mentalist side, how many Max Maven, Eugene Burger, and Tony Andruzzi wannabes are out there? Yikes. The originators can do it because they carved their path. Certainly, they were influenced by others, but Max is Max, Eugene is Eugene, and Tony was Tony. But it's been done--do something else.
I know I may be beating this drum a little loudly, but cookie-cutter mentalists are as big a problem as are cookie-cutter magicians. The whys and wherefores of your act are much more interesting than the whats.