Great advice from Anne Lamott.

"Almost all good writing begins with terrible first efforts. You need to start somewhere. Start by getting something—anything—down on paper. A friend of mine says that the first draft is the down draft— you just get it down. The second draft is the up draft—you fix it up. You try to say what you have to say more accurately. And the third draft is the dental draft, where you check every tooth, to see if it’s loose or cramped or decayed, or even, God help us, healthy."

"Writing a first draft is very much like watching a Polaroid develop. You can’t— and, in fact, you’re not supposed to— know exactly what the picture is going to look like until it has finished developing. First you just point at what has your attention and take the picture." 

Anne Lamott. Bird by Bird: Some Instructions on Writing and Life (p. 25 and 39). Knopf Doubleday Publishing Group. Kindle Edition.