Getting Serious About A Series

I'm going to write a series, and I'm so excited. I'd never really thought about it before, but after doing a session about it at a recent RWAustralia conference, seeing writer friends do it and loving finding an author has more books with the same setting and inter-linking characters - I thought 'why not'? (The fact that series are popular maaaay have swayed my thinking just  little as well.) I