I start out with a general premise or one image or scene as the embryo for my novels.
For STAR-CROSSED, the premise came after I read a romance novel which used sexual slavery as sexy fun and titillation. Horrified by the book's treatment of women, I had the evil thought--what would happen if men were the sex slaves, not women?
By switching the genders, I would be able to make my points about the inhumanity of such treatment and the corrosive results on a society as a whole. I would also have one heck of a romantic adventure setting on another planet.
I then asked myself what kind of heroine and hero did I need to tell the story I wanted to tell. The heroine would have to be from this society but against the harem system. She would have to be brave and willing to sacrifice everything for what she believes in, have enormous kindness and sympathy, and be totally ignorant of men. Mara d'Jorel was born.
The hero couldn't be a member of this society because the men on Arden are trained from birth to be protected darlings who don't worry their pretty little heads about anything. Something about him, beyond his looks, would have to attract Mara so she would consider taking a sex slave against her moral beliefs. I made him a famous scientist in Mara's field. ("He's not a man, he's a scientist!")
He would have to be worthy of her emotionally by having enormous love, kindness, and courage, but he would need some flaw which would drive them apart. The flaw would somehow reflect the premise of the story.
I decided that he wants a woman to love him for himself, not for his fame, looks, and wealth, and no relationship is more shallow and less likely to go beyond looks than sexual slavery. He would have to be insecure and distrustful of any woman's attachment to him. Earthman Tristan Mallory was born.
To develop my novel beyond this point, I used Ben Bova's (THE CRAFT OF WRITING SCIENCE FICTION THAT SELLS) plot and character development tools. He believes that plot is a characterization device. You must examine your character and find his/her one glaring weakness and attack it through plot.
The protagonist should have a complex set of emotional problems where two opposing feelings are struggling with each other. Emotion A vs. Emotion B. (guilt vs. duty, pride vs. obedience, fear vs. responsibility, etc.) He calls the conflict incompatible aims and desires.
This conflict should exist on many levels beginning deep within the protagonist's psyche and should well up into the conflict between the protagonist and the other characters. Resolution of that conflict is the story. He calls it an interior struggle made exterior by focusing on an antagonist (not necessarily a human enemy) who attacks the protagonist's emotional problem.
Using these ideas of Bova, I started jotting notes about the possible emotion conflicts within each major character and between the characters in STAR-CROSSED. Here are some of the things my notes suggested:
Mara & Tristan in unfeasible power positions, a struggle to regain equality between them.
Villainess Cadaran as embodiment of the evil government and the evils of the harem. Tristan's best friend Kellen must become Cadaran's bed slave and face the true indignities of the harem which Mara spares Tristan from.
Kellen vs. Cadaran, Kellen's attempts at escape -- major subplot.
Another plot conflict/subplot: Tristan's female friend Dorian must discover that Tristan & Kellen aren't dead, and she figures out about the harem planet and must come to their rescue.
Emotional conflict from this: Dorian believes herself in love with Tristan. Tristan uncertain of his feelings for her. Dorian's presence will tear apart the fragile bond between Tristan & Mara as his escape releases him from Mara's control.
Tristan's emotional conflict-- anger at harem society with Mara as representative vs. love for Mara as individual.
Theme: freedom through love, the importance of trust.
Kellen as foil to Tristan:
Kellen's emotional conflict-- hatred of society and struggle to retain emotional dignity.
his inner freedom vs. the hopelessness at being victim of an inescapable system.
Possible small conflicts:
Mara's housekeeper Novia acts as spy for Cadaran.
Mara's intelligent alien pet Floppy hates Tristan.
Mara becomes laughingstock when she takes a bed slave because her beloved dead mother was opposed to sexual slavery.
Well, you get the idea. At this point, I brought out some index/note cards. On each card, I put down a major scene or turning point in the central plot of the novel. Each of these scenes gives several important pieces of information on plot or character as well as moving the novel forward by causing change. Some of these scenes are obvious. The meeting of the hero and heroine, for example.
This card said:
Mara tracks down Tristan at hospital. She is shocked at his injuries yet attracted by his unfamiliar maleness. The nurse tries to throw her out. Tristan drags himself out of his coma-like state and reacts to her. Her kindness and her regard for this brilliant scientist as well as her attraction to him makes her decide that she will fight the government to keep him alive and out of the harem, whatever the cost.
After I finished the major scene and turning point cards, I was able to add cards of events that had to happen between these events.
I also made note cards of the subplots. (Each subplot must reflect or influence the main plot, and must change the plot for better or worse.)
I laid out the cards for the main plot, then I tried to figure out where the subplots would fit in with it. Most were just decisions in plot and time logic. Some were decisions about pace and emotional impact.
For example, just after the scene where Tristan & Mara finally admit their emotional attraction and hope for a true future between them, I put the scene where Dorian decides to rescue Tristan and declares her determination to marry him. This scene adds tension, not only because Tristan may be rescued from the evil harem (a good thing), but also because Dorian will destroy Mara's hopes for happiness (a bad thing).
Normally, I write the first three chapters at this point. Here, I learn even more about my characters and plot, and I discover holes in my plot logic and have to change my note card order. After these chapters, I type out a plot summary from the compiled note cards. I find even more plot holes which I correct.
The most important thing to remember is that the note cards and plot summary aren't carved in stone. The book will change as you write it. You must decide if that change is viable to your overall concept of the book and its premise.