I started using tabs to create calling scripts. I set a right alignment tab for the edge of the page, then when I need to mark a cue, I underline from the cue line to the right tab. If I need to include a note, I can type that in the space between the text and cue. I find it to be particularly seamless since I can create the formatting using keystrokes without accessing other elements. It also transitions well between Word and Pages, which is an added plus. For more precision, I sometimes add a "shapes" line to mark exactly where I want to call something. That can be a bit more time consuming, so sometimes I will add those in after the script is a bit more set.
You can play around with what is best for you as far as bold text/italic text/underlined text so that you're paying attention to the right things at the right moment. If there is something I particularly need to highlight, text boxes are always an option. And all of this functions quite well for blocking scripts, too.
In the attachment you can see a sample of what a script might look like, as well as where I placed the tabs in the ruler at the top.