Knowing what to do when designing is the key thing about graphic

Knowing what to do when designing is the key thing about graphic, understanding the element and the principles of design is very important and so from now onward i will be giving out important tips that you can use for your designs.
I call it 'the rules of designs'
1. Colours:
a. Use the colour wheel to create matching colour schemes that
are monochromatic, analogous, complementary, split complementary,
triadic, and/or tetradic. embrace colour. But use it wisely.