begin at point A, this is where you want the highest point of your arch to be, and connect it to B. now you have your highest point you can connect point C to point A. This will give you a brow with a perfect arch every time. using this method you can still decide how thick or thin you want your brow to be.
remember ladies, and my metro-sexuals, that each of us has a male and a female brow (all brows are NOT created equal). your female brow is your brow that is more beautifully arched and esthetically more pleasing, while your male brow is the one more unruly. when tweezing, you want to make your male brow look as close to your female brow as possible. and remember…you pluck a chicken and tweeze your eyebrows!