First: Make sure this is an idea you’re passionate about. A collection of stories that follow the same protagonist takes a long time to finish. That means you going to have to spend a great deal of time with these same characters, the same general location, the same rules you established. If you get sick of your main character at the halfway point, it’s over. Don’t be surprised that year five of your project isn’t as gripping as year one. But your love of the story and the sense of accomplishment will keep you going.
Second: Make sure you know from the jump how many books you plan to write, at least by the time you finish book one. If you’ve written everything in the first book and all questions and back-story have been explained, there’s no need for a sequel. The same rule goes for Hollywood. There are some movies that really, REALLY don’t need a follow-up. It’s a sign of a hack who’s too lazy to think of new ideas. Whether your book is a bestseller or collecting dust on the shelves, know when to bow out gracefully. The same brain that created your stand-alone novel can come up with another.
Third: Continuity is key. With each story, it gets harder and harder to stay consistent. Over time, your writing style might change; the voices of your characters may differ due to personal growth, or you may get so distracted by new plotlines that it contradicts previous ones. You find yourself rereading older volumes to recall certain plot points, powers, characteristics, rules you established early on that has to stay true through the series to maintain its integrity. Unless you wrote specific events that alter the rules, this is unavoidable. Cause and effect to any rule change has to be evident to the reader and any sudden personality shift must come with a good reason. Otherwise, you’re gonna get a lot of angry fans calling you out during book signings. Just say’n.
Fourth: Take a break. Work on a new project between books. Recalibrate your brain and sharpen your skills. This will reduce the risk of burn-out and help you remember why you loved the story in the first place.
Fifth: Not every story in the series is going to be the best. Don’t break your back trying to outdo yourself. Readers might like the first three books, but think the last two suck, or vise versa. Don’t expect the subsequent stories to be as sensational as its predecessor. Do the best you can and let it go. Different readers enjoy different things and you can’t please everyone. Also, know that the first book will always be the easiest to write in the entire project. The ideas were new, and you were free to establish the rules to your liking. The follow-up book will be slower, almost stunted in progression due to the foundation laid in the previous book. Each new entry will take longer to write because you need to rehash old events and reinforce this world you built.
This is not easy, and why I put myself through it is a question for my therapist. The worlds I create are too big for one book; there are a lot of areas to explore and questions that need answers.
There’s a great weight that lifts from your shoulders with each book, that you’re one step closer to completion and the story can finally be put to rest. You find yourself wishing and fearing that day at the same time. It’s hard saying goodbye to characters you spent years developing. They almost become real people. And if you’re anything like me, you have another book series idea in the back of your head and can’t wait to go through the process all over again. But that’s the life of the writer. Series-ly.