1. DON’T: Use ink.
DO: Use colored pencils.
I use colored pencils because they will not bleed through the pages and they give you lots of color options. Pens tend to smear or bleed through and can make a mess of your bible. Also, colored pencils can be erased if you make something incorrectly.
2. DON’T: Simply mark what grabs you.
DO: Create a system of meaningful symbols.
For example, in the picture above from my current study Bible, I marked the words “prayer” and “supplication” with a red underline that sweeps up and to the right and ends in an arrow.