The importance of editing
When I first started writing my Outdoor Athlete column, I tried to be perfect the first time. It never worked. I learned to re-write repeatedly, with Lori's help.
As I wrote my book, I fell into the same habit, trying to get it right the first time. I've learned now to mostly brain-dump the first draft- get it all out there. Then it is important to let it marinate for a while- for something short, maybe a week is enough. For a non-fiction book, probably a few months to a year. Then go back to it and edit it yourself for content, clarity, etc. Cut it down and tighten it up, usually reducing the word count by 10-20%.
Then get it professionally edited.
It was painful at first, but I learned a lot through the editing process. Having had little formal training, I needed the help my editor, Sam, gave me.
I've since read a few books on writing and recommend a couple:
SO get out and write, then put it away and edit it!