Use rule lines and different color pens.
You can change the appearance of the following features in OneNote — it's simple:
To add rule lines to your page, on the View menu, click Rule Lines, and then click the type of lines you'd like. Using the Hide Page Titles button and Show Page Titles button at the bottom right of the page, you can choose to show or hide the section page titles in the page tabs.
You can change the color of the tab and header area of each section. You'll try this in the practice session.
You have a range of pen colors and types to choose from with inking in OneNote. You'll see more in the practice session.