Nine Habits of Effective Designers outlines key principles for graphic designers to follow: 1) Keep designs simple and remove unnecessary elements; 2) Clearly establish a visual hierarchy; 3) Use principles of contrast, repetition, alignment and proximity (CRAP) to guide the eye; 4) Limit fonts to one serif and one sans serif; 5) Use a "magic number" like 12 for layout grids and type sizes; 6) Imitate respected designers but develop your own style; 7) Use color consciously and consistently; 8) Follow principles of alignment and grid layout; 9) Design at the intended size without scaling.