There are 2 ways to quit caffeine (or anything, really). You can go cold turkey, go through the headaches, and wait for them to end. And they will, but it will probably take several days. Drawbacks: headaches, obviously. Benefit: You will be off caffeine much quicker.
Option 2: cut back gradually. Mixing in decaf is a good way to do this, start with 25% decaf, 75% regular. Give it a week, then switch to 50/50. One more week, 75% decaf 25% regular, then finally all decaf. You may still get headaches but they'll be much less severe. You may have to stretch that out longer. Or you could start limiting the amount of coffee you have: if you normally have 3 cups, first week you have 2, then 1 1/2, then 1, etc. The benefit here is it limits the discomfort, the drawbacks are it takes much longer, and you may never get off the stuff completely.
I too am a caffeine addict, took me a long time to give up coke (the cola lol) completely. Coffee I'm not giving up-yet, though I have limited myself to no more than 2 cups a day for a while now, lately I've been doing just one cup most days, and before lunch only