Hydration is important, like Ledonna says. I used to be strict about 8 glasses a day; I've relaxed into just making sure I have a glass with each meal (3x a day) plus every time I have coffee or a snack (also ~3x a day).
Using an unflavored lip balm may help -- the ones that are sweet will tempt you to lick it off, even if it's unconscious, and the licking makes your lips drier.
For a while I quit using moisturizers packaged as lip balm because they're pricy and many don't work. I was just putting plain solid shea butter, cocoa butter, coconut oil, etc. in little pots and using those. But then my brother gave me this Evan Healy lip balm (check Whole Foods and local natural foods stores if you don't want to pay shipping), and WOW does it ever work. It feels super luxurious, smooth but not greasy, and using it two or three times a day my lips are less chapped than they've ever been in winter (and I ski and snowshoe, and I have a cold right now).
I think timing is also critical with lip moisturizers. I try to apply the same way I do other moisturizers: after a shower, after washing my face, and before and after sun/wind exposure.
