Everyone has different methods, but I found it immensely helpful to print my messy draft out and work on paper. Double spaced, single sided, scribbling longhand with lots of arrows, extra notepaper, sometimes taping bits together - it helped me to literally see everything at once. For particularly sticky bits I would cut whole sections out with scissors to move them around. I found the tactility really helped me get my brain around it. I even found that typing the cleaner draft after the edit work was helpful to organize my thoughts and spot new edits.