Many people get blocked at the very start of the writing process because they believe their writing has to be PERFECT from the get-go, with perfect word choice, perfect sentence structure, perfect spelling, and perfectly formed ideas.
Does this perfectionist attitude block your writing in the early stages?
I have news for you: Your writing does NOT have to perfect, especially not at this initial stage. Think of the earliest version of a piece of writing -- the draft even BEFORE the first draft -- as the Zero Draft.
You can also call it a Discovery Draft or Notes for a First Draft.
Thinking in terms of Zero Draft allows you to write for the purpose of discovering what you have to say. You are less stressed out about the outcome, which in turn can lead to bouts of brilliance! In your Zero Draft -- of a chapter, thesis statement, or dissertation abstract -- let yourself freewrite. You have the freedom to experiment with wacky ideas, type incomplete sentences, and let the automatic Spell Check underline every word. You don't care. Your job at this stage is to get ideas out from your brain and into your computer. Type, type, type. Don't censor, don't judge. Heck, you can even use an elaborate font in a bright color.
In Zero Draft writing, allow yourself to be messy, wrong, unsure, and grammatically incorrect.
If you get tripped up or distracted by word choice decisions, sentence arrangement choices, and the like, take the pressure off of your writing by titling the top of the page: Zero Draft.
Remind yourself that you can -- and will -- come back to a particular word choice, idea, or spelling question later. It's OK to leave incomplete sentences, dangling participles, and spelling that puts Spell Check into overdrive. These gaps can be filled later, when you put on your Editor's hat during the revision phase. For now, get some core ideas out of your head and into the abstract system of signs known as written language. This is already an accomplishment!
PS: I wrote this post as a Zero Draft.. then went back and fixed spelling and organization. See? It works!