I'm honored when new writers come to me for advice, because they wouldn't ask if they didn't value my opinion or believe I had something worth sharing. But rather than repeat myself each time I'm asked, I've decided to dedicate a page with my advice and resources all in one place.
PERFECT YOUR CRAFT
It goes without saying that the first step new writers should take is to perfect their craft. I recently delivered a master class for YA Thriller Con my best writing advice here: Master Class with Eva Pohler.
One of my favorite books written on the craft of writing is an oldie but goodie: John Gardner's The Art of Fiction.
HIRE AN EDITOR
Once you've perfected your manuscript to the best of your abilities, you should hire a professional editor--not a copy or line editor, who will basically proofread your work, line by line, but a developmental editor. A developmental editor (also known as content editor) will help you with the "big picture" issues, such as character development, plot problems, and your use of dialogue.
Back when I first started writing, hiring a developmental editor wasn't in my budget, so I swapped manuscripts with cirtique partners. Some advice was helpful and some wasn't, but it was a start. Eventually, I managed to find a developmental editor who agreed to edit the first fifty pages of my manuscript for $300. I later took a course from her through the Writer's League of Texas that was worth its weight in gold. I highly recommend Sara Kocek and her team at Yellow Bird Editors.
DECIDE HOW YOU WANT TO PUBLISH
If a professional editor thinks your book is ready for the reading public, it's time to decide if you want to publish traditionally (through a publishing house) or on your own. The traditional route usually requires an agent. Before submitting your manuscript, do your due diligence in finding those who represent your genre and are open to taking on new clients. You can research agents at Agent Query and Publishers Marketplace. You will also find resources on those sites for writing good query letters. Most authors receive countless rejections before they receive an offer of representation, so don't let that discourage you. William Golding, the author of The Lord of the Flies, was rejected 21 times before Faber and Faber agreed to publish what has now become required reading at most high schools.
While you're waiting to hear back from agents, you should start writing your second book. The first question any interested agent will ask you is, "What's next?" I have found that creating a stand-alone novel with series potential is a smart way to start.
If you don't want to put yourself through the emotional rollercoaster that comes with submitting to and being rejected by agents, you can choose to self-publish; however, the road to becoming an independent author is just as much of an emotional rollercoaster, though in different ways.
If you are self-motivated and a jack- or jane-of-all-trades, you can become a successful indie author. The advantages, in my opinion, outweigh the disadvantages, which is why I chose this route. I enjoy being in control of my publication schedule, cover art, and storylines. I also love marketing and finding new ways to help readers to discover my work. But, although I once succeeded in getting my books on the shelves of Barnes and Noble stores, it was too difficult as a one-woman operation to keep up with returns, so I pulled my books. Now they're only available for purchase online--though I do have many readers who order their paperbacks through brick and mortar stores.
Here is a slide show that accompanied my presentation to several writer groups, including the San Antonio Writers' Guild and the Fredericksburg Writers' Group: The Road to Successful Self-Publishing. The slides provide only an outline of my talk, but they still may be useful to you in making your decision about how to publish.
If you want someone in the industry to guide you through the process of becoming a published author, who can provide you with an editor, a cover artist, a publication schedule, and possibly a book tour, the traditional route may be your best path. With that guidance will come a lower payout in royalties per sale (others will get their cut before you will) but may also mean more exposure that you couldn't have managed on your own. A traditional book deal also brings with it more prestige than self-publishing--though the stigma against independent authors has significantly reduced as people become aware of how much money many of us make.
If you want to be in control of your career and aren't afraid to work hard and learn new things, independent publishing might be for you. I work very hard for the money I make, but it's work I enjoy immensely.
BUILD AN AUTHOR PLATFORM
Whether you publish through a traditional publishing house or go it alone, you will need to build your platform. A "platform" is your readership or your fan base. A number of books are available on the subject, but here's a simple slide presentation I gave to a few writing conferences in recent years: Building an Author Platform.
My best advice comes from the motion picture The Edge, starring Anthony Hopkins and Alec Baldwin, in which one character assures another, "What one man [person] can do, another can do."
Best of luck!