One approach is to start with a character who shares some background with you. Readers like getting an inside scoop on a lifestyle or occupation. In the first in Barbara Seranella’s Munch Mancini series, Munch is an ex-heroin addict who becomes a mechanic – just like Barbara did. But Barbara also told me that the more books she wrote featuring Munch, the more Munch became a separate person from her.
Other people who write series start from scratch. When my friend Deborah Donnelly started her Wedding Planner Mysteries, the main character's job was something that just came to her in mystery writing class. Every other aspect, though, was carefully planned out. Because Carnegie is 30-something, she is young enough to date, but old enough to have some history. She lives on a houseboat in Seattle, an interesting location. And even the wedding planner idea, while spontaneous, proved to be perfect upon further reflection: her job means there will always be a new group of secondary characters to follow around throughout the course of a book.
Lee Child told me that his initial set-up was quite calculated . He says, "I wanted a protagonist who was uneasy and not-at-home in civilian society, and so decided that an ex-army brat and ex-army officer would fit the bill. Plus, I needed him to have extensive familiarity with the investigative process, so the extension to ex-military policeman was a no-brainer. Then, having read extensively in the genre all my life, I wanted to opt out of the damaged, angst-ridden, wounded trope in terms of his personality and return to a simpler, purer form of hero as was known fifty or a hundred years ago ... much more like a Western-style hero - not John Wayne necessarily, but certainly Gary Cooper.”
Whether you chose to draw on real-life or well-researched circumstances, be sure to give your main character troubles. Trouble is no fun in real life, but it makes for good reading. Is she afraid of heights, did he grow up in poverty, did her husband leave her for another man? Unresolved troubles can be revisited in future books.
“Be careful not to nail down all the particulars of your characters' lives in the first book,” says Elaine Viets, author of several series. “Leave room for ex-lovers and spouses and long-lost relatives. It will help your plots later on.”