My journey for The Risen was a pretty pragmatic one. I've procrastinated for years (in part because I didn't feel ready though) but last Nanowrimo I told myself to complete a project, and so I wrote it in a month, doing around 2,000 words or more a day. I began with a theme and a couple characters, and an idea of the world, and that was it. Previously I had planned too much and what I was coming up with didn't feel very natural. With Nanowrimo, the goal was to let the characters lead the way, and to write an adventure-style narrative; and overall, to go for quantity over quality. It was a lot easier afterwards to edit, as the hard work had already been done. When you're so involved in your story every day, you live with it, and ideas come easy. I didn't know the ending until half-way through, but when it came, it was very natural.
To edit, I printed it all off double-spaced and then just read it in my leisure, with my red pen in hand. I'm a proofreader and copy editor for my job, so this part wasn't difficult for me. If you write in this way, don't be surprised or disheartened by the number of mistakes you make, as you'll be writing quickly.
The key for me, beyond grammar and punctuation, was editing sentences so they were concise. You should need to cut a lot. I avoid repetition of favourite words and phrases. If something doesn't sounds right - don't be afraid to reword. If it doesn't sound right to you, then it won't sound right to someone who doesn't know what you're trying to say. Where possible, remember to show and not tell. Keep all the rules you've learned in your head as you edit, and you can't go far wrong.
I let a couple colleagues read it too. Get someone you trust to be honest with your work to take a look, and take on board any suggestions they have.
I'm completely aware of the limitations of my novel - it's just a bit of fun. I submitted it to a couple places that were open to horror submissions, one being the Curtis Brown agency. I was buoyed when I got a non-generic rejection, saying it was better than a lot of stuff that get submitted. In the end, I just made a simple cover and put it on createspace, which in turn gets it put on Amazon Kindle, and it's now in the Kindle Unlimited scheme. While trying to get an agent or a publisher, there's no harm making it available through self-publishing.
In fact, if it sells well, you show you have a proven record of sales and readers, which will always be favourable. You can also begin earning money straight away. If you're a 'nobody' don't make it expensive. You need to get people to read it and review it and rate it. Make it cheap, make it free whenever you can. Set up your author page on Amazon and Goodreads. Connect. Post about it everywhere, such as Facebook groups, on Twitter with the right hashtags. There are accounts out there with thousands of followers who will retweet you. If you use createspace you can buy physical copies of your own book for around $3 - $4. Use these books in Goodreads Giveaways. Check out fiverr.com for some super cheap book promotion (check reviews first). (I used one called bknights who generated 300 free downloads on the day it was active, which dropped to 50-60 for subsequent days, so it does work. The Risen was on the front page in the horror category for a while!)
What comes from this is a feeling of addiction. I literally can't wait to finish my next novel and get it out there. I just wish I'd done this 10 years ago, though I may not have been ready then.