I have people all the time tell me they have wanted to write a book. They dreamed about it, sat down to start, got distracted with life, and eventually quit altogether. This isn't an exhaustive list, but here are a few places that you can land that might help.
Rachelle Gardner is a publishing agent and super down to earth. I find her advice helpful and not pretentious. She seems to rally behind the author and not just the next buck to be made.
She has a great post titled, "Sometimes you Fail, and it Sucks." For an author, that's always an applicable blog title.
She also has some great links here.
Lucid Books is the publishing company that I used...and loved. Their blog always has some practical tips on writing, publishing, reading, and selling effectively. This post titled, "Mastering the Art of Writing," that has several great resources linked up. They also have a helpful post called, "7 Tips to Improve your Writing."
Most of what they write is easy to put into practice and makes you think through your writing/publishing process.
Douglas Wilson's Wordsmithy is a quick easy read. He explains the power of words and how to use them most efficiently. I found this helpful in my intentionality with word choice.
I could link up hundreds of helpful sites and resources, but at the bottom of all of this is to answer these two questions:
If so, what excuse are you currently using as to why you haven't started?
What fear is whispering to you?
I've chronicled a bit of my writing process at "How the Heck did you have Time?"
People often tell me that they want to write. My advice every time is...then start writing. Everyday, write something. Tell your fear to back off and start writing.