One of the most versatile principles in graphic design that can help you out of all sorts of problems.
Why you don't just go with what your computer monitor shows you?
Contrast issues that are grounded in color: Vanishing type, Vibrating type, Busy backgrounds and widely varying backgrounds.
When do I put light type over dark backgrounds and dark type over light backgrounds. It's not at the 50% mark.
Does form follow function and what does that mean for finding new an different solutions?
Hue, Saturation and Value define colors; learn which one matters most for contrast and its relationship to legibility. How to assure good contrast.
Learn about the simplicity of design, that computers don't design for you, avoiding BYC design and JTBD design.
Clear thinking can help rid us of misconceptions about what graphic design is for.
There are many false notions about creativity. Learn what they are and what creativity really is.
There are true principles about art that have been discovered. Learning and using them makes better art.