It's crucial to create compelling, believable characters. The reader has to care about the characters in order to care about what happens to them.

One helpful exercise is to write a background sketch of each major character. Include everything you can imagine about him or her: name, physical appearance, emotional makeup, age, occupation, background, family, habits, quirks, tastes and preferences, hobbies, education, etc. You may not use all of this in the book, but fine details and subtle shading make a character come to life.

When you first invent a character, it's like meeting someone superficially at a cocktail party. As the book progresses, you will get to know your central characters far better. Plan to go back after a while and check to be sure your main character's actions and responses are realistic and true to the person s/he turns out to be.

Avoid cliches like the absentminded professor or the ditzy blonde. Truly memorable characters often have a feature or two that runs contrary to type. The gruff detective may have a soft spot for opera or gardening. The matronly spinster librarian haunts a trendy after-hours club. Like real people, your characters should be multi-dimensional people with particular fears and aspirations, strengths and soft spots, secrets and sensitivities.

I like to think of plot structure as a mountain climb, though without all the cumbersome equipment and messy risk.

In the beginning, the climber approaches the mountain, sizes it up and gets to know the territory. In novelistic form, this translates into introducing the central characters, the setting in which the story takes place, and the situation as it stands when the story begins.

Next, you need to introduce a problem or conflict. In a mystery, this may be a crime or a dead body. In a romance, the heroine might discover that the man she loves is really an alien from Zog (where he has a two-headed wife and twenty-seven alienettes.) The middle of the book is devoted to this problem and the main characters' attempts to resolve it. As the book proceeds, the stakes should get higher and higher, building tension and suspense.

Near the end, the conflict or problem is resolved. The sleuth determines that the butler did it. The star-crossed heroine finds that she prefers her former lover, an accountant named Herbert, to the intergalactic scoundrel. Loose ends are tied up and the tale is finished.

Subplots are secondary stories that enrich a book by adding interest and complexity. These may involve the central or subordinate characters.

Note: The central character must change as the result of the events in the book. A young lawyer learns to put love and security above ambition (The Firm). A really foul-tempered fish discovers that nastiness has its price (Jaws). Unless the main character changes, there is no reason for the story to be told, and the book will be an entirely unsatisfactory read.

A great deal can be explained and explored through conversations between characters. Try to give each character a distinctive voice. Keep in mind the way people speak to one another in real life.

Avoid stilted or overly formal dialogue. In normal conversation, people often use contractions, fragments and slang. Try studying a master of dialogue like Elmore Leonard. His characters are known for their memorable, distinctive speech styles.

Consider the situation in which the conversation occurs. Parents (hopefully) speak to their little children very differently from the way they talk to their bosses. Colleagues in a field may sprinkle their talk with professional jargon. Lovers or close relations may use pet names or other expressions of intimacy.

Note: Eavesdropping is an excellent way to train your ear, not to mention fun.

Be careful about the way you present dialects or accents. You may be better off indicating that the character speaks with a drawl (or whatever) than trying to offer a phonetic rendition on the page. This can be jarring and distracting.

Again, think of a mountain climb or a really good aerobic workout (without the sweat). Your book needs a warm-up, a period of increasing exertion and intensity, and finally, a cool-down. Try to vary the tension and mood as the book proceeds or you risk boring your readers to death or leaving them panting and exhausted.

Think balance. Heavy dramatic scenes should be followed by something lighter. Dark events are well served by comic relief.

Choose a location that will serve your style and story best. Some writers enjoy setting a gritty police story in a bucolic little town. Others prefer the mean streets of a big city. Any site is fine as long as you do the following:

1. If you are using a real locale, get it right. Nothing stops a story colder than putting the train station where the high school is or having a character drive the wrong way on a one-way street (unless he's headed for a ticket or a crash.)

2. Whether a place is real or invented, make it resonate through details. Name and describe the locations your characters visit. Explore the experience through all of the characters' senses. How does the place look, smell, feel, sound? What, if any, historical or emotional connection does the character have to the place? What interesting or relevant events have happened there?

3. The best settings are so real and vibrant, they seem to serve as central characters in the book.

You can choose to tell your story from a variety of viewpoints:

Author Omniscient - In this viewpoint the writer can enter the mind and offer the perspective of any character. Different chapters can be told from varying points of view, usually in the third person. This viewpoint offers maximum freedom and flexibility and many writers prefer it.

First Person - One (or more) of the characters tells the story in the "I" voice. Events are limited to the narrator's knowledge and experience, but the viewpoint can provide powerful emotional insight and connection.

Shifting perspective - Different chapters or scenes can be told from varying perspectives. Avoid shifting perspectives within a scene. This can be disturbing and confusing.

Other - I have left out other valid viewpoints (e.g. the second person or "you" voice) because of the difficulty in execution. Any perspective is fine if you are able to implement it effectively.

Note: Any of the viewpoints described above can be used in the past or present tense.