Like many others, I always said, "I'd like to write a book someday." Like many others, I didn't think I could do it. I've been making up stories in my head for years, but they were always snippets - little bits of the action that would keep me occupied until the meeting was over, my name was called in a waiting room, or I was trying to drift off to sleep. Every time I tried to make a story, from beginning to end, I got stumped. Too many questions about every detail in the story.
My dear husband, the podcastaholic, kept telling me he would hear these two words from author interviews: Just write. When I started getting serious, thinking I really wanted to do this, like, for a career, I cruised my favorite author's websites to read any advice they might have. The second most important advice I got was basically, "just write, edit later." If I stopped to edit all my mistakes and change my mind on wording, my progress would be agonizingly slow. Even slower than it is now working around family and my other part-time work.
Just write. It doesn't have to be the beginning of your story at all. When I started the first book I finished (I started two others first, but decided I needed to be more seasoned for those particular books) it all formed around one scene I had in my head. Coincidentally, that scene was the beginning of the story, but in the middle of writing I will jump around. For example, I might be in the middle of a naughty scene where I left off at home, but when I'm able to write outside of home (cough-during slow times at work-cough, cough), I'm not always comfortable writing about body parts slapping together. Cue an action scene, maybe an epilogue.
All writers work different, but I found the story told itself. Many times, I would incorporate details as I was typing. Literally, as I was typing - describing a supporting character: Tattoos? Why not. Mohawk? Sounds interesting. I would write individual back story details of each character, but have no clue of what the back story was. I would write the characters in a conflict with no idea how to get them out of.
The solutions would present themselves at random times. The best were when I was on long walks or runs. I'm a horribly slow runner so a few miles takes me awhile. Plenty of time to let my mind mull over the everyday things and then move on to my story and the characters and let scenes play out in my head. It was awesome. Until winter hit. Inspiration still strikes me, thankfully. As long I keep thinking about my story.
Good luck newbie writers! I'm a newbie myself, with only one book under my belt and a second almost written. I received so much support from the other professionals in our field, I want to pass it on; compile my hours and hours of internet searches in a few short paragraphs of what worked for me and what might work for others.
Happy typing :)