How can I start practicing meditation, yoga, or tai-chi?

Recently I've been thinking a lot about ways to relieve my stress and other mental problems such as OCD and ADD and I have been hearing that meditation, yoga, tai-chi, etc. can possilby help with these problems that I have been suffering with all my life, but I am very confused as to which one would be the best for me.

Also, if I find out which one would work the best for me, how would I go about finding someone that could teach me these things? Or is a book a good way to go? If a book is a good way to go would you suggest one of those "The Complete Idiot's Guide to..." books?


Is my hair addicted to dandruff shampoos?

I have dandruff that responds well to over-the-counter shampoo. Ergo, I have been using the stuff almost exclusively for ten years. No brand in particular, sometimes zinc pyrithione (the blue stuff!), sometimes coal tar (the smelly brown stuff!). Anytime I switch to non-dandruff shampoo for like three to four days straight, I get my dandruff back. I worry that I might be addicted to dandruff shampoo. Should I worry?


Why can't I cry anymore?

For the last year or so, I haven't been able to cry anymore. And when I do, absolutely no tears come out. My eyes just water up, but there are no tears. Is this normal? Should I be worried?