I've got a couple of ideas - see if you can get a manicure - it doesn't matter what your nails look like now - but when they look nice you might stop
A more expensive idea is nail tips - impossible to bite and it hurts when you suck your thumb
Wear a few thumb rings on the one that you suck - it might remind you what you're doing as soon as you feel the metal against your lips.
Good Luck!Ways to stop me from biting my nails and sucking my thumb?
well, there's the age old trick of sticking you thumb in codliver oil so that it tastes so bad you won't want to put it in your mouth...or get it wired shut for a while so you can't..but basically, if you're already concious that it's a problem, you just need to be more self-disciplined about it...when you go to put it in your mouth, stop!
and think about what it does to your teeth...if you don't have an overbite already, I'm amazed.
If you refuse to grow up and use your head, then rub your hands with jalapeno peppers once a day!
Usually the methods that work best, given that you truly want to stop, are those that remind you that you're indulging. So, putting a bitter substance on your digits will bring your habit to conscioussness where you'll be better able to stop the sequence.
Having written this, you ought to consider the fact that thumb sucking (tsing) has some real benefits, assuming you have no negative health affects (malaclussions, etc.). Tsing is legal, cheap, available (convenient), does wonders for concentration and allowing one to fall asleep more easily, lowers the heartrate which means that it easily puts one into a meditative state, a state that has been determined to be very beneficial, healthwise, and more...
The same goes for nailbiting, unless you have negative health affects, and nailbiting is more socially acceptable.
You may want to visit the FAQ section of www.thumbsuckingadults.com for a more detailed analysis of this question.