From 7 Tips for Writing Crime Fiction, written for Writer’s Digest.
6. Decide early on if you’re writing a series or a stand-alone.* Don’t introduce that great character only to kill him off at the end of the first book of a 22-book (and counting) series. Don’t ask me how I know.
*Realize that a book can turn on you at any time, and often will.
Read the whole piece on Writer’s Digest here.