Let me just say that I have NOTHING against fake blondes. Maybe they're just girls who want to have "more fun" or something. And I'll admit that sometimes it actually looks good! I only have one piece of advice for these girls- it's more of a plea, really:
COVER UP THOSE unsightly ROOTS!
Seriously. It either looks like you did a head-stand in a pile of dog crap or your infrequent hair-washing creates a greasy build-up, making your hair appear 10 shades darker. Which is it?
If you're going to go blonde, the more power to you. But please, none of that skunk-striped, half-and-half look. Just my two cents. :)