One very very important thing I learned once by watching What Not to Wear is never tweeze the tops of your eyebrows.
I know I have mentioned my love for all things Stacy and Clinton before, and I may have even mentioned this little tweezing tip, but to me it bears repeating because I am a daily tweezer. Yes, all my fair haired friends, when you have dark hair and like your eyebrows to accentuate your eyes, and not overwhelm them, you feel the need to tweeze on a very regular basis.
When you keep the tweezing to under the brow, across your eyelids, you make sure to maintain a nice arch. You can reach up into the brow a bit, but never ever ever tweeze above the brow. Over-reaching the bounds will cause the need for regular maintenance that could have been avoided if you had followed this extremely important advice.
And that is the extent of my eyebrow parable, which is to be interpreted (or not) any way you wish.
ps This is not a picture of my eye, but I have also learned the art of lining the top lid only with a thick swath of liner. This is my new favorite make-up discovery (no parable intended).