I would just use the highlight color code in a document on the computer. Same idea but without wasting ink, paper, and money. Most document programs have a highlighter feature. I know both microsoft word and google docs do.
Actually, I am not done with first draft because I am only on chapter fifteen, which I did not finish.
I am redoing it, because I have ideas nagging at me that requires me to change the first draft so things make wee more sense to me.
I could not do the editing and just continue with the story, but then things will be wonky come time for the editing and second draft. And I hate to stare at the things that need changing immediately and just continue writing.
I could do that, but do I want to do that and become a glutton for later punishment.