Ombre Hair Coloring at Home?

Just a little background on my current hair:

A year ago I decided to go from jet black to platinum blonde at home (BIG mistake).  I fried my hair, had to cut about 6 inches off, and my hair has been on the road to recovery ever since.

I've been using nothing but semi-permanent hair dye every 2 months for the past year.  I have my hair back to my natural color (medium ash brown) and in pretty good condition.  I like it how it is, but I do want to brighten it up a bit.  So I've decided to color my hair Ombre style at home.  Don't worry, I have plenty experience with coloring at home, so please don't tell me to go to a professional.  I don't even have the money for that!

I was wondering how you would go about it.  I was thinking the best bet would be to buy a highlighting kit and pull strands from just above the ears, down to the nape of my neck, and from the back crown of my head, down to my neck.  That way, the upper layers of my hair aren't colored, and the highlights only peak out from the bottom. 

I've never tried any Ombre hair coloring before, so any tips or better ideas are greatly appreciated!  Thanks! :)