Make Characters Real

Use basic needs--food, water, sleep, shelter--to REALize your characters. This coordinates closely with a previous suggestion to remember to use the five basic senses in your writing. It applies to what your characters experience as well. Other common human characteristics include desires for sex and companionship; pleasure-seeking/pain avoidance; and intellectual pattern-seeking and a need to understand. The basic needs apply to all life forms we know about, historic and current. There's no reason to think they won't continue into the future.

If you're writing speculative fiction, horror, sci-fi, or fantasy, you might give a character an opposite desire or lack of a need to differentiate your work. Asking readers for a total "suspension of disbelief", however, could backfire. A universe with which they cannot identify at all strains readers' abilities to remain in the fictional experience. Even in the Known Space worlds of Larry Niven characters don't violate all the familiar: The Kzin mate; the protagonists of The Neutron Star search for similarities, learn, and grow; inhabitants of The Ringworld build homes.