1. Name Your Game

You must know what novel to write before you start considering how to write it. We'd all be surprised if John Grisham started writing eroticas, or if Ludlum's next book was for children aged 8-12.

To decide your genre, you must consider the type of novels you most enjoy. Whichever it is, it is the type of novel you would be best at, because you would understand the general storyline, what makes the novel enjoyable, all the pros and cons.

Generally, there are two types of novels;
The Reflective: where there is less emphasis on the stroryline. This type of novel is centered mostly on the characters themselves; their fears, their weaknesses, their unusualities. The prevailing mood is usually somber and philosophical.
This is not to say there will be no action whatsoever; there will be the usual problems to solve. However, the novel's chief aim is to bring out the characters in all intensity through their dialogues and thoughts and descriptions and histories. An example of this type of novel is The Horse Whisperer.
The Active: this kind of novel centers on the storyline. This is not to insinuate that the characters are shallow. It only leans more toward pace, movement, action without much time for chit-chat and speculations. The James Bond series is a typical example.

Most novels are usually a mixture of both broad categories. However, a well-written novel will usually lean toward one or the other of these extremes.