How to prepare to write a series

The coffee house book is not part of a series. It's the first book in a collection of stories, but each book can be read and appreciated independently.

I am, however, also working on a different story line that will be a series. (I know, I know. I promise I'm not brainstorming this other story to avoid the coffee house book.) So I'm preparing to write this series in a similar way to preparing for the coffee house book collection.

The first steps for the series is an outline. I have an overreaching story line in mind, which I'll be breaking into smaller outlines for the individual books. I know some of you start foaming at the mouth at the mere mention of outlines, but in order to maintain continuity, I have to be able to look through notes and make sure I'm in line with where I need to be.

Once I have the outlines, I'll write the character biographies, and then I'll be ready to start writing. Sounds simple enough, doesn't it?

For me, the key is making sure I'm consistent throughout the series. I have to make sure that, as I write the individual stories, I keep the overall series story line in mind. For that purpose, I'll be using story cards. I'll write the major series plot points on index cards and stick them on a board in order. Then I'll take the plot points and separate them for the individual books. I'll then use the sets of story cards to develop the individual outlines for the books.

I'm looking forward to working on the series. Of course, the coffee house book has priority, but when I'm ready to start working on the series, I'll have my plan.

Have you ever written a series? If so, how did you prepare for it?