John Steinbeck wrote all of his books by hand. In particular, he wrote The Grapes of Wrath in its entirety on yellow legal pads, scribbling in a nearly indecipherable and quite small scratch. It was his wife, Carol, who loyally typed up his first draft, and she is known to have done the work of cleaning and polishing as she went, improving the language and writing. It's crucial to have that second layer of writing to improve our rough thoughts and scribblings, and while someone else might do it, you can easily do it yourself.
Many writers still write by hand. Jennifer Egan is one writer whom I've heard writes all her first drafts by hand on legal pads just like John Steinbeck. It's an essential first step; and it automatically builds a second draft into the process of typing it up. Maybe you've written paragraphs and pages by hand, and now they're scattered about your life, appearing in various notebooks. Today, spend some time pulling together the pieces that you have and typing them up into one document. As you type, you'll find yourself improving the work, cutting down on words, not bothering to type paragraphs that are a waste of time, choosing better words where you got repetitive. You'll be doing important work to make the writing coherent in your mind, and you'll be taking the first step to improve it.
At the end of a typing session, you'll often find yourself with a better vision for the work - and you'll have an improved work on your computer too.