I have always enjoyed writing. Everything I've done has involved some sort of writing. I used to write poetry, songs, and many many stories. The problem hasn't been getting started for me. The problem I have always had has been losing interest in whatever project I am working on. So how do I get around this problem? I'll get to that soon.
First you have to get an idea. This is the time when you get really excited about a story, and figure out all of the major plot points. What is the world like? What are your characters like? My first impulse is to sit down right away, and start writing. That is not what works for me. If it works for you then I salute you.
The next step that I took was to research the world. If everything in your book is going to come from your mind then this is a bit different than going to the library or google, and looking up everything you need to know. For instance, what are the popular religions in your world? What kind of religious sayings are used? Something like "May Kratuk's wisdom guide you" may be something that is commonly said. Maybe Kratuk is a cruel deity, and something like "May Kratuk notice your death 15 minutes after you reach paradise" would be more appropriate. What are the major institutions in your world? What is the government like? What does each of your characters do on a normal boring day? This all becomes a lot easier if you are only using facts that you already know, but don't think that you do not need to do any research. Don't ever make the assumption that you know everything. It will make things a lot easier if you have all of these things figured out beforehand. I have a notebook where I am keeping track of these things. Let's say you need to know how many representatives sit in the legislature. It's a lot easier to look that up on the government page in a notebook than it is to go look through your entire book for the one time you mention it. The "making it all up as I go" approach doesn't really work for me. Sometimes you have to add something for the story. The story is going to be in a constantly evolving world, so leave some blank space in the notebook to add new notes as you write.
The last step I took to prepare was to set up an outline for the book. Before when I would write, I would always lose interest in the journey from point to point. I broke down the entire story into chapters. Each chapter has a specific starting point and ending point. It has been a lot easier for me to stay interested in the journey rather than just the major plot points now. I just treat each chapter as a short story, and focus on what I can do to make this chapter interesting and fun. So far the book that I am working on is the longest story I have ever written.
I hope this helps someone out there, and please add your tips if you have any. I would love to read them!