Are you an author or a writer? What I mean by that is--is this your hobby, or are you hoping to make a career out of it? There is nothing wrong with either option. In fact, hobbyists might have something on me. They can just write! They don't have to worry about the business side.
But if you're going to do this as a career, you can look at it one of two ways: 1) You are your own business. Your name is your brand. 2) You are a freelancer. But freelancers are self employed, so you're really still your own business.
If you had any other kind of business, you would have a business plan. Authors need this as well. I've decided that I've queried for the last time, so I came at this as a self published author. (I'm not planning to release my novel until June, so if I get an offer from one of the fulls I have out, I can change my plan). But I think if I were traditionally published, I could easily alter my plan to accommodate that business model. I'll be producing the same products, the only thing that changes is whom I'm collecting my pay from. I have felt great since I created my plan. Having a realistic production schedule made me realize it might actually be possible to do an extra project this year, or at least start one. And I feel like I'm in control of my career now. I'm no longer waiting on someone else's acceptance. I write quality books. I'll pay for quality editing. I produce them. They may not be bestsellers (that depends on readers), but they get my name out there, they build a platform, and they build a backlist. I strongly recommend if you want to do this professionally, you make a plan. I found a great example of a self published writer's business plan here. It's a three part series, so you can find the other two parts here and here. I was able to use this as a template, but Denise Grover Swank, the plan's writer, was further along in her career when she wrote this than I am now. I had to get creative to make some parts work, but I did it. If you know you need a plan, but feel overwhelmed by this, send me an email. I can send you a copy of my "newbies" plan, or if you have one you're working on, I'm happy to help you work out the problem areas. If you're not interested in self publishing but want a plan, take out the pricing strategy, don't worry about the release date in the production schedule, and use everything else. (You still need the financial plan for things like conferences, business cards, and an editor if you use one before submitting).