Sorry I was at the dog park. Okay I know everyone (hairdressers)has rejected the cap for highlights but they are the best way to do touch ups. Because you can pull just the roots through the cap creating loops of dark hair the ends of your hair stay protected under the cap. You get a better color match and less damage.
To late for that now. Low lights would be to use a dark color haircolor not bleach and do the foils that way. If you want low lights figure out which dark color you want the really blonde hair to be. MAKE THEM TEST STRAND IT ON YOUR REALLY LIGHT HAIR. I wrote that big because if hair is to damaged it will pick up the base hair and that is bad since some base colors are green (ash), violet, or blue. I would be nervous bleaching or highlighted hair unless your hair is pretty strong.
Okay just don't do what these girls are doing. Please wash the bleach out of your hair and condition before you try to pull off the cap.