(As a sidenote, we are surviving here at Casa Rappaport Agency. My husband still has swine flu, I may or may not have it, and we are taking preventive measures because we don't want the cat to get it. Yes, cats can catch swine flu. Odd, I know. She is confused and sad about not being able to sleep on the bed, since my husband is occupying it. I get the couch. Also, I can type, but I must take breaks... onwards to the topic!)
Anyway, one of the most common questions I'm asked as an agent is this one, roughly paraphrased:
"I have written a wonderful book. It is the first in a series of X books (where X>=3), and I am now shopping it around to agents. Should I write Book 2 in the series?"
Now that's all well and good. As a reader, I love big, fat series. As an agent, not as much. And here's why: if I can't sell the first book in your series, then I'm not going to be able to sell books 2 through X for you. So you're going to have spent however many months of your life writing the next three books in your series, and I'm going to have to tell you to write them off as practice.
But surely that doesn't happen, you say. You point to authors who have done just that, and then their agents have sold the first six books of their series all at once, and see, they should have been writing the next books.
You have to think of this practically. Do you want to spend the next ten years of your life writing something that will never be published? Do you really want to invest that much time into something so risky? Or would you rather write the first book of your series, outline the others, and then start a new, different project? Because once that first book of yours doesn't sell, I'm going to ask for what you have next... and wouldn't you like to have something to show me?
Of course, there is the common caveat I give to all writers. If the book is burning inside you to the point where you will literally go mad if you don't write it, then write the sequel. But if you don't have that intensity and desire, then write something else.
Stretch your wings as a writer. Try writing something in an opposite POV than the one you just used in your prior novel. Try making your protagonist a different gender. Switch between genres. Think of new and interesting things. And experiment with them because that's the only way you're going to learn as a writer.
It may take you five novels to get published, but if each of those novels is a different one from the one before, then you know what happens when Novel #5 sells? You'll have the experience and the writerly toolbox to whip out the sequels to it. =)