Hi Ben,
A question for you: are you funny? Do you make people laugh? Do you make your
friends laugh?
Please, before reading any further, reread the last three sentences and take a few minutes to come up with an honest, brutal and unflinching answer. You do not have to share this answer with anyone but you need to be honest with yourself. This may sound bold, but, I
am funny. I
do make people laugh. Both friends and strangers, often unintentionally.
While you're thinking about that question I'd like to respond to a couple of responses to your original post. If you can't be arsed with that scroll down until you see your username in
bold.
First, Gary Grace:
Let me guess at some of the words that you may be using in your act. 'mysterious'-she was my old maths teacher, 'Psychic'-I went to a psychic the other day. I knocked on the door, and she shouted,"Who is it?", so I left. 'Medium'- I went to one of these the other day, and he was laughing at the gullibility of the public, so I lost my temper and hit him. I was arrested for striking a happy medium.
You are a very naughty boy! Go straight to your room! Great jokes, though.

Second, bmat:
You want to do a mentalism routine and be funny? Isn't that against the mentalists code?
No. Now, you could be joking (!). Assuming you're serious: No. In fact:
NO!
magicmindben, I am a budding mentalist. By that I mean I've spent the last couple of years moving away from close up magic towards mentalism. And by that I mean I've stopped performing close up and have started performing a 45 minute mentalism stage show, which, to be honest, is a new learning experience for me, a completely different kettle of fish.
I use humour a lot in my act. I don't tell jokes but use my interactions with the audience, and the surrounding environment, to allow humour to arise. This sort of humour is spontaneous but is founded upon having a fully scripted act. It's probably a defense mechanism (I had a very violent and brutal childhood), but I'm naturally funny. I can make people laugh just by looking at them. It is, therefore, very easy for me to be funny because I've had a lot of practice at it. But also, it's very easy because my act is scripted. Knowing what I am going to say at any moment throughout the act gives me the freedom to be spontaneous and to use the unexpected as sources for humour. As paradoxical as that sounds it is the truth.
Earlier on I asked you a couple of questions. Are you funny? Do you make people laugh? If you naturally do, I suggest you interact with the audience in the same way that you do when you're with your mates. If you don't have the inherent capacity to make people laugh then I suggest you get acting lessons from a reputable tutor, preferably one specialising in comedy.
Just occurred to me: what makes
you laugh? What do
you find funny? Humour is infectious. If you find something funny, and can communicate that effectively, then other people will too. Not everyone, but enough.
You could use a joke book but I wouldn't. I would much rather rely on my own inherent capacity for humour, which we all have (you included!) to introduce comedy into my act.
So, my advice in a nutshell, for what it's worth, is this: if you have a natural capacity for comedy use, and develop, that. If you don't, then get acting lessons (or whatever the equivalent is for comics; comedy lessons?) and cultivate the capacity for comedy.
Hope that helps. If not, er, then I'm sorry for wasting your time.
All the best
Gary