But first you have to think up a character and that's sometimes really, really difficult.
So, you start with a physical type.
Since I'm only average height, my heroines tend to be that way, though there is one that is about 5'8" or more in one of my unpublished stories. I had someone in mind when I wrote her, a physical type, though her personality and that of the model are not anywhere near alike. But I thought, since I'm not very tall, what would it be like to have a tall heroine? One who could do more than I could do physically?
And I proceeded to write her as taller and what I thought would be the advantage certain height would give her. To even things out, I gave her a companion who was much shorter and of a different coloring. To make matters worse, I made the buddy pregnant so the heroine would feel obligated to protect her. Okay, you have the physical type. You know her hair color and eye color and how tall she is and whether she is model thin, physically fit or not so fit, voluptuous or flat chested, good legs, what have you. Then you work on what she does, like her job or her education or her goal in life. That isn't really difficult to come up with, though you ought to put her into a situation where she'd likely be found. Or accidentally found. Say, she's a geologist, you have her at some sort of oil rig in the Gulf during a hurricane or in a desert filled with people who hate women and don't think they are qualified to do more than bring them food and warm their beds.
(Sheiks are currently OUT as heroes. Bad guys, maybe, but heroes, nuh-uh.)
So, she now has a job. You can put her into a situation on the job, which is likely, or you can put her in a grocery store when the place gets robbed, in which case, you might as well have her a nuclear scientist or floor scrubber, it doesn't make that much difference, unless her particular skill will assist her in some way to get her out of a bad situation. Say, she's a geologist and the bad guys stick her in a cave and expect her to rot, but she realizes this cave has to have another opening and using her skills as a geologist or part-time spelunker, she gets herself and the other people left there with her, to safety.
That's good.
Having her stuck in a cave and being a seamstress might not help. Geologist, yes, seamstress, not unless everybody tears their clothes. But a seamstress might be good if they need parachutes made out of some cloth that happens to be left lying around the bottom of the cave...but that's another thread we won't use readily.
Okay, she has a job and education and what else does she need? She needs a particular hang-up to make her all too human. She can't be Wonder Woman since you aren't writing a comic book. She has to have something wrong with her, either physically, mentally or something weighing her down personally, like an alcoholic brother who is on the run from the cops, just so he can show up to foul up her life.
She has to have this flaw. Nobody wants to read about some perfect woman. The readers want to be able to associate with this heroine, to know that they could be in her shoes, so you give her this defect...like fat thighs or a loose tooth that makes her talk funny or some hang-up from her youth, like she was raped or her parents beat her or she was really fat or had some kind of problem, like bad breath or crooked teeth, that made her separate from the rest. People hardly ever write stories about cheerleader-types who seemed to have it all.
Not unless they really didn't have it all and nobody knew their inner pain because they were able to hide it so well.
Okay, she's got hang-ups, defects and some kind of mental inability to make her fit in with everybody else. After you've alienated her from most of society, it's cool
The reader can relate to her and if you give her a good sense of humor, the readers will love her. Now, you have your character. You've got to put her in a situation that will cause her big problems. Usually it involves a man, 'cause you have to get the guy in there somehow.
And, carefully, you have to make the hero have the exact same amount of problems as the heroine. Give him the job, the background, the hang-ups (they should be different from hers or not that close so he can say "I know what you mean" and actually mean it.) He can't be able to understand her fully and vice versa. The romance writers who have gone before me have labeled these things internal and external conflicts. Each main character has to have a pair. You can't have a romance where these conflicts are not present. Editors will not buy the story if you are lacking these things for both main characters. And they have to be clearly defined.
Let's take my new book, Kisses to Go.
Abby Porter is short, has strawberry blond hair and aquamarine colored eyes and a dynamite figure. All good. Unfortunately, to make her human, I have to give her such a good heart that everybody takes advantage of her (internal conflict) and put her in a situation where she has to go against her vow not to let anybody take advantage of her again. She does well to make her vow and leave the bad situation behind her, but she only has a limited amount of money at her disposal because the rest is in the hands of her recently ex boyfriend. She sets off for a vacation in England, something she's always wanted and nothing seems to go right from the plane ride to how she can enjoy her vacation and still eat. Of course she folds. She ends up cooking for everybody and then ends up helping out the hero. Ah, the hero. Boy, does he have problems. First of all, he's a snob. He hates Americans, but that's because his mother who left him when he was young, was one.
He's also particularly oversexed, but doesn't realize it until he meets the heroine.
He needs money, even though he looks rich as hell what with his huge palatial estate filled with very expensive things. He has no cash and needs it to fulfill a promise he made in honor of his dead older brother. He needs help but can't ask anybody for it because he's a snob.
What he ends up needing is exactly what Abby can give him. He has to humble himself to ask for her help and further complicates things by asking her to pose as his fiancee. That right there is a hell of a problem. And he needs to get money for his project, somehow, someway.
So, his problem meets her problem. She doesn't want to help but it is her nature to help, completely and fully, those she cares about.
He has to ask for help and give something back, and he ends up having to act as if he cares about Abby, despite her being American. And, guess what, he ends up falling in love with her (the oversexed thing comes in to play here) and doesn't know how to handle it. Also, they both have to pretend that there is nothing wrong with his money situation and he has to find a way to pay Abby back.
Both internal and external conflicts make the story and characters what they are.
And the problems have to be clear-cut and understandable.
They can't be something that can be easily fixed. The complications need an infusion of money, trust, food, help, police, psychiatry to be solved. Major things. Not any kiss-the-booboo type things, but major work.
The major work and the complications become the plot of the story.
Fill in the blanks. Start with a name of a character. Build a personal profile and flesh the character out. Add traits you like in a person, traits you dislike to make them interesting. Or things you think another person would find intolerable, but then you have to make the character endearing. Faults do that. A huge snob who is horny and nearly bursts with need yet cannot act upon it in any way to maintain an image is cool. A woman who vows never to fall for a needy man again comes face to face with a guy with an honest problem that she can totally solve and he's a nice person who makes tons of promises and makes good on them. And they both realize they cannot possibly fall in love because he's such a snob and she's going to leave soon.
Works.
Works well.