I'm currently at the editing stage of the first book in a series of four or five books. I've got this constant nagging worry that I'm going to miss bits out that I don't think of until I get to book three or four or five. Anyone else feel like this when you're writing a series of books?
It's tying the last book to the first that does it. You realise you are missing some foreshadowing way back when, change a few things which then have to be reflected in the books in between and, before you know it, chaos reigns. I've done it many times. Mind you, this has a lot to do with my serious lack of planning.
I have just finished editing book 1 in my series of at least 4 novels.
I have outlined my ideas for the next three novels. I have the beginnings, middles and ends, but things will be clearer when I list my working chapter titles. They should ensure I keep my plots and storylines as straight and as clear as I can make them.
Characters are not a problem as I have not killed the ones I intend to use in future novels.
I doubt you can ever avoid it entirely.
IMO it's secondary characters who are most likely to be problematic as you should know your hero/heroine's backstory inside out, even if you haven't put it down on paper. As an example, I killed off a female character in a fairly nasty way but late on realised it would be interesting if she re-appeared later in the series. That meant an awkward re-write as the hero had to believe she was dead, which affected his relationship with two other characters for the rest of the story.
You could write a profile, including backstory, for every character who appears in the story, adding each event involving them as you go along. This would help avoid pitfalls, but it's still no guarantee and I've never bothered. Some writers do, some don't.
I'm on book three, and no real problems so far. Though my cast isn't huge.
Best of luck :)