I used to have the same problems that many of you have mentioned with
lip/ear/face picking, and
I'm pretty convinced at this point that it's a result of 1) too much adrenaline
and/or 2) not enough dopamine. Anyone with anxiety problems and/or ADHD is likely to have this kind of chemical imbalance (i.e. me), and I'm a firm believer of addressing the causes of these kinds of habits as opposed to focusing on covering up the symptoms.
So far I've had the best luck reducing skin picking by avoiding adrenaline-inducing habits and finding things that will increase my dopamine levels (in a healthy way).
I mean, the reason why the picking is so addictive is that we get little bursts of dopamine from these kinds of grooming activities, which actually goes back to an evolutionary adaptation for keeping ourselves clean and free of parasites. Also, have you ever noticed that when you drink (note: this is NOT a hint to use alcohol to deal with this!!!), you don't have the urge to pick? Or how about when you're eating or when you're extremely happy? Well, those are all dopamine-upping activities, so of course you don't want to pick. To put it in a few words, picking is just another way of self-medicating for lack of dopamine.
So - things to AVOID are excess caffeine, sugar, blood sugar ups/downs (especially letting yourself get hungry), stimulants, sleep-deprivation and stress (duh).
Some of these are adrenaline uppers, too much of which will induce anxiety and will make you want to pick as a way of calming yourself down.
GOOD things are exercise - don't think calorie-burning as much, those activities can up your adrenaline even more - yoga and tai chi are awesome. Going on a 10 minute walk while listening to some relaxing music does wonders, especially if you spend a lot of time sitting down and working. Also, eating lean meats can help (don't over do it!) because you need amino acids to build neurotransmitters, especially seratonin.
I've found it also helps if you can break the cycle for a little while, especially if you have a formal event coming up that you want to look good for. Good tricks for this are to put vaseline/neosporin on the picking target-zone, especially at night so it can heal up while you sleep. Also, as weird as it sounds, if you're a female lip-picker you should try loreal's infallible lip gloss. there's something about the texture of the gloss that covers the rough parts so you don't really want to pick at them.
Hope this helps!