I am an aspiring author, but I intend to start publishing soon. I have several ideas for potential books; however, they are all series. I am hesitant about starting my writing with a series. What if it isn't successful? Then I would be stuck with a series that is going nowhere. If, however, I wrote a stand-alone book, I could easily move on whether or not it was successful. It seems that a stand-alone would be the way to go. Unfortunately, all my ideas are for series. Also, there have been best-selling authors who have started out with a series. J. K. Rowling and Christopher Paolini come to mind. What do you think? Should a beginning writer start with a series or a stand-alone?
Really simple answer is this:
Write one book. Tie up all the loose ends. Make it one complete story. But imagine it as book one of a series. Don't let we the reader know that -- it should be undetectable to us, but you will know there's potential for a series.
When sending to agents and publishers ensure you include the golden words: "Stand-alone novel with series potential"
If it sells really well and they want a series, then you've got the ideas ready and you can crack on with the second book of what is now a series!
Few publishers will want to take on a series from a debut author. What if it doesn't sell too well? Now they've promised a series that they won't want to publish.
Have the potential there, but ensure book one stands alone perfectly on it's own merit.
(And Good Luck!)
Bonus: You mentioned Rowling, well ... it's true Stone leads into a series, but it has no loose ends. Sure, we wonder what happens next to Harry, and we're pretty sure Voldemort isn't gone forever, but the entire plot of Harry's first year is completely wrapped up. Compare with the Half-Blood Prince, where they find the locket with the note. There has to be something next from the 6th book because of that loose end, but the first doesn't have that same need for a sequel.
From @Paul A. Clayton's comment:
It might also be worth noting that publishers do not want to break up a series among different publishers and so may reject one book if another in the same series is rejected. From the "Author's Afterword" of Lois McMaster Bujold's Young Miles:
"Seven months later Warrior's was returned unread from its first submission, because they'd decided not to take the revised Shards and didn't want to break up the set. This was devastating at the time, but I was in fact grateful later."
The examples of Paolini and Rowling are not useful as blueprint for a different reason than that stated in the comments: they are exceptions. Overwhelming success is rare, not the rule. It happens to a small percentage of published works only, and you cannot plan it. What you can plan, though, is a more moderate, general success. And this depends largely on simple skill. If you can write, that is, if you can form pleasant sentences, construct a gripping plot with a satisfying end and cast engaging characters, then your book will sell.
As almost all published writers have said, getting to this point is only a question of diligence and a lack of narcissism.
Lack of narcisssism means: Don't be so in love with your ideas that you cannot let a failed attempt go and continue to the next work. Write a book. Finish it as best you can within a reasonable time (no more than a year or two) then submit it. If it does not get published, write the next book. And the next, and the next, and the next, until one book is published. When you have published a few books, maybe go back and rewrite the first unpublished books with your now advanced level of skill.
I don't know your level of skill, but since you are apparently unpublished and probably an average writer, you very likely need to train more. Brandon Sanderson explains this very well in the videos from the writing class he teaches (available for free in his YouTube channel). Most continually unpublished wanna-be-writers are too emotionally attached to the one "great" idea they had as a teenager and that they have been struggling with for the past ten or twenty years. They are so in love with themselves (because their idea is themselves) that they cannot let it go and so they are stuck forever in something they can't get to work and cannot see why other people don't value it as much as they do so they feel misunderstood, etc. The problem is that they misunderstand the art of writing. They believe writing is about expressing yourself, while in truth it is first and foremost a craft that you have to learn. Expressing yourself can come after that, if you want to write literary fiction, but even then you first have to build a solid base of writing skills which allow you to actually express yourself in a way that others can understand and relate to.
This is the point where unpublished wannabees like to say: But, this or that writer was an international bestselling success with his first book he wrote without ever having written a single word before! Yes. Sure. But how many such writers are there? Maybe a hundred in all of history. Or, if you want, make that five hundred. And how many writers who have tried that but failed are there? Millions each year. Everyone I know has tried to write a novel, been rejected, and given up (or has secretly and to the detriment of his self-worth kept revising it for the past twenty years without even his friends wanting to read all of it). And how many writers have been published after writing ten or so unpublished complete novels? Millions and millions! Every single book worldwide and in all of history except for the five hundred immediate success-wonders. The vast and overwhelming majority of books on the market is by writers who have written one book after another until they got publshed! How did they manage that? By not being in love with their first book, or at least not in love enough to find themselves unable to get to the next book.
So the real answer to your question is not: series, or: stand-alone. While I don't think Mac Cooper's answer is false, what will really get your fist novel published is not that it is self-contained, but that it is well written. If it is the well-written obvious first part of a series, it will get published. The editor will ask you to write the second and maybe third part, before they publish it, because the question in a well written book is not wether the market will accept it, but wether the author can continually deliver good quality. That's the real problem with series'! If you submit a finished trilogy and its great, it will get published!
Editors and agents get overwhelmed with unbearably bad writing. They don't reject books because they have too many good books to publish, but because the books they reject are just plain bad. If you write a good book, it will get published.
So just simply write the book that you want to write, send it out and keep sending it out until you are sure you have exhaused all options, and in the meantime start writing your next book. Then send that out and in the meantime write your next book. And so on, until one book gets published. If you don't give up – and I don't mean: don't give up on that first book, but don't give up writing new books – you will gain the level of skill that will eventually persuade an editor. And then you have a wealth of drafts that you can turn into new works quite quickly.
In reply to the comment by Mac Cooper:
You may disagree, but do you have the publishing experience to support your disagreement? I prefer to believe those writers who have been publishing successfully or the agents who have sold their books.
In my answer, I sum up what bestselling author Brandon Sanderson says here: http://www.youtube.com/watch?v=CbL-84SkT4Q ("writing is not about inspiration, ideas, or luck, it is about skill") and here: http://www.youtube.com/watch?v=I3JlBLG7xOI ("lay the 10 year project aside and write the next book").
Agent Rachelle Gardner writes: "Sometimes a first-time author will get a contract for a three-book deal if the series is strong, so you definitely want to mention it’s a series" (my emphasis; source: http://www.rachellegardner.com/writing-a-series/). Agent Barbara Poelle answers the OP's question with: "don’t believe everything you hear. I have sold stand-alone books and series across the board, and whether or not there is a franchise possibility has nothing to do with my consideration of representation whatsoever. Just be good. I like that part the best." (my emphasis; source: http://www.writersdigest.com/online-editor/literary-agents-unleashed-answers-to-questions-youre-too-afraid-to-ask ).
The rest of your comments either supports my answer (Rowling and Paoline being exceptions is my argument for not using them as examples, so your statement that they are exceptions does not oppose my answer) or irrelevant to my argument (if your book gets published by the 8th publisher you submit it to, you still have spent your time well if you didn't wait for the reply but wrote the next book in the meantime – you should always be writing the next book, no matter if the first does eventually get published or never).