End Writer's Block:
The easiest way to end writer's block for me is free writing. Sit at the computer (or pick up pen if you are a longhand first person), and start writing. If you can't think of what to write, start describing your computer or pen and paper. Then look out the window and write about what you see. Or, you can write about your last or next meal. It doesn't matter what, just write. Then as you get going, put one of your characters in the scene. What would they think of whatever you are writing about. Write for at least 15 minutes. Then go back to whatever you're writing, and you'll be surprised how the creative juices start to flow.
Do Your Research:
Wherever your book is set, find out about the area including what types of trees, flowers, fish and even bugs are there. Don't have your characters chasing fireflies on San Diego beaches, or going on a grunion run in Florida. (Grunion are fish that swim to shore to lay eggs on southern California beaches. You need a fishing license and can only catch them with your bare hands.)
Okay, I don't always follow my own advice, but the more days I don't write, the easier it is to find excuses not to. I don't write on Sundays, but try to edit or write a few hours the rest of the week. Some days it's only a few minutes, but books or articles are written one page, one word at a time.