Write likable characters, agreeable women, genteel men, characters with easy personalities and gorgeous faces. Write characters your readers want to have over for dinner, want to introduce to their families, want to take to a movie.
Give your characters no disagreeable traits. They should have no strange quirks, no odd anecdotes—nothing to make the reader believe your characters are anything but typical, average folk. Make your characters simple, bland, and easy to digest. Like gruel.
Keep your characters in serene environments. People typically appear craziest when exposed to pressure situations so keep your characters far from any conflict. Do not write villains into the scene, and don't even think about adding a plot twist.
Make your characters beautiful. Readers love attractive characters. All the men should be cut as though they live at the gym, and the women should be thinner than their personalities. Give them tan skin and blue eyes and sun-kissed hair. Basically, all your characters should look like they came from an episode of Baywatch.
You're looking to create a Barbie/Ken Doll from words. Your characters should be beautiful and perfect, and their lives should be easy and simple—no complications, no conflict. They should love everything and everyone, and they should never do anything that might upset the reader. Completely disregard characters like Austen's Emma or Nabokov's Humbert Humbert. They have nothing to do with the task at hand. Readers want a character they like.
If, by chance, your reader falls asleep at page ten, they will have a nice, soft text full of fluffy scenes and doughy characters to use as a pillow.