I swear and, as God is my witness, I had a terrible prejudice against anyone who wrote a series, or planned to write one before their first book was even picked up. I laughed at anyone who wrote a complete series and had no agent to push it. Back in the day, series books weren't as popular as they are now. Today, it's almost a given that large independents and big publishers like/love to sell a series. Two-book, trilogies and large series packages are more popular than EVER. Multiple books are actually favored by publishers--it seems to be the advantageous way to hook readers, build a fan base, and at the same time, launch a debut author. If you've written a standalone today, chances are excellent that you will be asked to follow it up with a sequel or more books that belong to a series--your special universe. I was left in the dust, from my own account, all those years ago, up until just fairly recently.
So, I want to formally APOLOGIZE for my narrow view and ridiculous exclamations.
I've completed a trilogy, edited it with my agent, and turned it over. It's now going out on submission.
I can't tell you what kind of hard work this project cost me. It was a mountain of writing, revising, editing and titling.I was hesitant every step of the way, wondering if all of this effort could possibly pay off. Then I realized, what did I really have to lose? I'd made them standalones, with only slight references to each other that could be removed very easily. So I just about guaranteed myself a possible sale--somewhere--even if it was small press. When the work was done, I was satisfied, and so was my agent, who said "I think we really have something hear."
I can remember J.K. Rowling penning (starting) Chamber of Secrets before her first book was picked up. Now that's MOXIE! Or call it blind faith. Not only that, it was her intention to write seven books! Look what happened to Twilight, Hunger Games, Wool, Divergent--they went on to success--becoming huge breakouts.
Now that my YA trilogy is over, I mourn it. I miss my characters. Terribly so. I can't believe that I did this, stepping up to the plate and accomplishing my most difficult writing project ever.
If you have a series in mind, go for it! Don't let anybody stop you, and field those rejections for solid and valid comments. I think you will eventually sell. Even if you have to self-publish, I believe you will garner a much larger fan base with multiple books.
Good luck with your series. Press on, have faith and reap the rewards.