Great ideas are easy to come by in the wonderful world of writing-I write on the wall ideas all day AND night long. I have ideas for books, articles, screenplays, essays, poems... you name it. And they really are great ideas (I know because after a while, someone else thinks of it and makes a ton of money), but that first word gets me each and every time. It must be perfect. It has to be right or I cannot go on.
I self edit as I write, yet I'm a one-draft-deadline writer, and here's why: the first chapter of The U-Haul Murders is the Littlest Angel/The Last Day; it's been rewritten more than one hundred times and I'm not joking. No matter how good it is, by my standards for fellow readers, it can always be improved. Knowing Shakespeare and the Bible can be rearranged and changed for improvement - two perfect works of art (Shakespeare=all his work) - doesn't make me feel any better or edit any less.
As for the writing? I'm going to have to change it up a bit more. No more "freewriting" because I know it's just a bunch of rambling with no intentions ever of going anywhere. Instead, I'll have five minutes of completely unedited REAL WORK that has a preplanned purpose. Every other day I'll write, and the next day, I'll take five minutes (and only five minutes) to edit the piece and improve as needed.
Practice makes perfect; nobody's perfect.