Bernard Malamud once commented, “The first draft of anything is suspect unless one is a genius.” I am suspect of the “genius” caveat, and am more in agreement with Ernest Hemingway that “the first draft of anything is rubbish” (although he expressed it more colorfully).
However, the hesitance to commit words to paper, actual or virtual, because you know they’re rubbish can stand in the way of getting the first draft complete—and it’s not until you have a complete first draft that you can work on making it less rubbishy. As with so much advice about writing, the direction to “just get the words on the page” is easier said than done.
A trick I’ve developed to overcome this hesitance is to mark anything that is especially rubbishy with <angle brackets and purple font>. (Any marking will work as long as you use it only for this purpose.) For example, in the last sentence in the first paragraph, I originally typed “although he expressed it <in more spicy language>”; I didn’t like the word “spicy,” but I didn’t want to get bogged down at that moment in coming up with exactly the right word.
This trick enables me to plow ahead with my half-baked ideas and sentences, knowing that I won’t lose track of the especially egregious issues in the editing process. Another benefit is that there are some days when I’m in more of a “finding exactly the right word” frame of mind, and I can easily search for angle-bracketed sections to fix.
This works not only with individual words, but with sentences and even paragraphs. However, don’t use the marking for more than a few consecutive paragraphs. That’s not using it for the intended purpose, it’s just providing a visual illustration of the fact that the first draft will be rubbish, and that will be more likely to freak you out than to speed you up.