I think it differs for everyone. My eyebrows are very dark brown, but when I dye my hair black, I use black eyeliner to color them.
But! You're talking about lightening and changing the color. First thing, dun bleach your eyebrows. Or shave them off. If you're like me, and you have kinda thick brows, I would say to shape them first. I use the Basic Brow Tutorial by Michell Phan. When I get to a computer I can give you the links.
EDIT!! Here is the link to the basic brow tutorial : http://www.youtube.com/watch?v=PugziVUikEg&feature=relmfu As for lightening them, start with putting on foundation.
Once that's done, this is what I do to lightenmine:
1. Lightly color your brows in with white pencil. Don't color the whole eyebrow, just swipe the pencil across them a few times to basically cover them.
2. Take a qtip and softly rub the white across the brow. This spreads the color a little bit.
3. Now lightly, using a sponge and liquid foundation, blot the foundation onto your brows. I mean, like super lightly. If there's a bunch of clumps when you do it, take a brow brush (I used an old toothbrush) and comb them out.
4. Step back and look at your brows. If you can still see most of the color, and you want to change the color to a light color, repeat step 3 until the color is lightened more.
5. Now you can draw on your brows with either colored liquid liner for super thin ones, or take an eye pencil and "color in" your brows alone their natural line.
This works for me. It may not work for everyone, but you can try it if you like
I also found these Ah, the help I can be when I have a computer How To : Change your Eyebrow Color -
http://www.youtube.com/watch?v=puIBd4fhEiQ"Scene" Make-up Eyebrows -
http://www.youtube.com/watch?v=AdekmF1MpAo&feature=related