Writing is a pain in the ass.
You boot up the computer, open your word processor and stare at that god damned blinking cursor, mocking you, daring you to do something. The more you realize you don't know where to start, the more you realize you're not starting, and then that's all you're thinking about. You step away from the computer, pace the room for a bit, check Facebook, Twitter, Instagram, YouTube, for the love of god anything other than actually writing.
It's OK. This is normal.
But you need to check that shit, sit your ass down and write (I say to myself in the mirror). Honestly, I don't usually feel like writing at all, even on good days. But I do love having written something, if that makes sense. Forcing words out is grueling, sometimes tedious, but the reward is in the completion, when the pain stops and you look back and realize you've created something cool. Much like exercise: you can talk about doing it all you want but unless you get up and make it happen nothing's gonna change.
I start with this because it's the biggest obstacle to overcome. It's why, when asked for advice, so many successful writers answer with "Sit Your Ass Down And Write" (see also: "Ass In Chair"). It sounds like a cheap answer, and it may be, but it's as honest as it can get. Most people give up right here, but if you push through, carry on, cowboy up (or whatever your favorite idiom is), you'll be ahead of the game.
GARDENER VS ARCHITECT
George R.R. Martin introduced the idea of two schools of writers: gardeners and architects. Gardeners prefer to write by the seat of their pants; that is, they don't have an outline or plot or even a real idea of where they might be going. They plant the seed of a story and let it grow organically, much like a garden. Architects, however, like to follow a meticulously detailed blueprint (or outline, if you will). They plan every step, every plot twist and character arc long before they set fingers to keyboard. Both of these methods have their pros and cons. With the gardener method you run the risk of spending lots of time and energy writing just to realize the story is going nowhere and needs to be rewritten or scrapped entirely. But it can be exciting to let yourself (the writer) be just as surprised by the twists and turns as the reader will be. The architect, however, stands a better chance of avoiding drastic rewrites (HA! right) or having to scrap the book, but they run the risk of sucking all the surprise out in the planning phase so that writing the actual prose feels more like a tedious chore (since they kinda sorta already wrote the thing and know everything that happens). No one way or the other is right or wrong, it's up to each writer to decide what works best for them.
I'm an architect that leaves a little room for gardening here and there. I plot the entire outline for the book, detailing the specific events of each chapter, what happens, how the stakes are raised and how each scene leads to the next so that I know where I'm going and what I need to focus on. But sometimes my notes are vague enough to let me figure out more specific details later. Where the outline for one chapter might be several pages long, others might look more like this:
'Chapter 6: Character A meets Character B at a cool location, they discuss lunch. There's an explosion.'
Once I have the outline completed I'll print it out and cut it to pieces with a two-handed battle ax...I mean red pen, and make plenty of changes before I even begin writing. This helps me get started each time I sit down at the computer because I don't necessarily need to think about what I'm going to write that day; I just look at the notes then spin them into captivating and compelling prose that transports the reader to another world revealing deeper meaning to the human experience that leaves them gasping for more...no big deal.
Thing is, even with an outline it's not always easy to string words together. In order to avoid procrastination and track progress, writers set daily word counts for themselves. 1000 words per day tends to be a good standard to shoot for. At 1000 words a day (if you're consistent) you can have a 90,000 word novel completed in three months (I did that math all by myself). Once you get used to it, 1000 words goes quick and can be done in an hour or so under favorable conditions.
The hard part is consistency.
It's not always a convenient time to write so you have to make time between work and family and other responsibilities. Maybe this means you stay up late at night to write once everyone else goes to bed, or you write on your lunch break, or before school, or between household chores, or maybe you get up at 4 in the morning like a psychopath. Whatever your method, the important thing is you get the words down.
Again like exercise, sometimes you gotta warm up to it, start slow. I started by aiming for something small like 250 words until I got used to sitting at the computer every day. Once I had that part down I cranked up the word count to a whopping 500 words per day. Once THAT became easy I started hitting 1000 words. It became such a routine that I now get anxious and miserable when I don't make progress.
When I got going on the first draft of WAKE OF WAR, I was consistently knocking out 2000 words per day five days a week. Before I knew it, the book was done. Well...the first draft was done, which is very different than being DONE.
Once the first draft is done I'll print a copy at the local office supply store. The first draft of WAKE OF WAR was around 120,000 words, came in at 462 pages and cost $40 to print. There's something about seeing the words on page that help me find errors and get a feel for how the book really reads. There's only so much computer screen I can stare at before my eyes melt out of my face. I'll carve this bad boy up with the bloody ax/red pen then go back and make the changes to the document file. I only print the one copy, but the book will continue to go through round after round of edits. The first few are major, fixing things like characters whose names change halfway through the book, and actually writing in the parts I skipped by hitting caps lock and typing FIX THIS LATER. As I get going on this I may send the book to a few trusted beta readers who can look past some of the glaring issues they know I'm going to fix and give me input on big things like story structure problems or character issues.
At several points through this process I convince myself the book is the biggest pile of garbage I've ever seen. I hate it, I've read it 3,000 times in a row and if I have to read it one more time I'm going to throw it in the fire. Then I come back to it and realize it's actually pretty good. I find my motivation again and before I know it I'm reading the book like I don't know what's going to happen next. This neurotic flip-flopping is a common aspect of being a writer. Get used to it (I say to myself in the mirror again).
Eventually the book will reach a point where it's as good as I can get it on my own and any further attempt to edit will only result in pointlessly moving words around or simply making it worse. It's at this point, where you're sure it's the best possible book it can be, that you can begin to query agents (if you're seeking the traditional publishing route, self-publishing is something else entirely that I'm not particularly familiar with so I'll leave that topic alone). It's good to keep in mind that the book will continue to go through revisions even after you get an agent and that agent sells it to a publisher and the publisher hands it to an acquisition editor then copy editor, more beta-readers and so on.
Writing is work. It's not always gonna be sunshine and sudden inspiration, but it doesn't have to be torture either. It's an obsession. There's something to be said about dreaming up a world and characters and story from nothing, especially when someone else reads it and goes, "You know, that's not complete garbage."
Well, that's how it is for me any case.