Cold turkey is the only way to do it.
I quit caffeine in Feb I think the Saturday before the superbowl.
What happened was I drank 16 ounces of strong black with milk to lighten it up so my teeth didn't look like I was from England. No sugar. Everyday. When I didn't want a buzz I drank decaf, I love the taste of coffee to the point where I have been called a snob. I have my cheapo favs and that gourmet shyt. It's never candy. No syrups and sugars, honey, chocolate and vanilla. Beans, water, and something to lighten it.
Anyway I went to bed at 10pm one night after a day when I didn't drink any. I did a lot of shyt and was genuinely tired. I wasn't lagging because of not drinking coffee but I had a full day and when 10pm came I was yawning and shyt, ready to sleep. I went to bed and woke up at 2am head pounding. Stomach felt sick, head pounding, light sensitive...a bullet to the head mightve felt better or at least alleviated the pain radiating throughout my body. I made my way to the kitchen and made a cup of strong black and **boom** like someone simply hitting an off switch everything went away and I felt like a million dollars. I knew then I had to let the shyt go.
Whether it was then or sometime in the future I knew I had to quit and just let it hurt for the time being then be over it. I had some coffee the Friday before superbowl Sunday and haven't had any caffeine since. I've been drinking water, no tea, no juices, no decaf, no milk, no Gatorade, WATER! And haven't had the slightest headache or migraine or anything. In fact I haven't used advil, aleve, Bayer,ibuprofen since either and for one reason or another I was always popping those.