How to NOT dye your scalp when dyeing hair?

So basically I'm a blonde and I'm using a semi perminent dye to go a medium brown. The box with the dye says to wait 24 hours after showering to do it, but we asked my hair dresser and she said do it right after showering. And also, when we dye it, is there a way to prevent dyeing my scalp skin?How to NOT dye your scalp when dyeing hair?
Don't worry about your scalp. . . Semi-perminent is not going to stay on your scalp!How to NOT dye your scalp when dyeing hair?
you can use a semi-permanent color on clean hair, however when you rinse it out you shouldn't use shampoo if possible and wait as long as possible to wash it (at least a day or two) so the color holds better. as far as not coloring your scalp, I think that's pretty much impossible.
Honestly, your scalp shouldn't get dyed very dark. I've known plenty of friends to dye their hair, and even when the dye got on their scalp- it washed off, but the hair color stayed. :)