I'm my own worst critic when it comes to writing just about anything - especially longer articles. I have no problems writing those initial drafts, but when it comes to editing, I just keep editing for hours and days on end. This is one of the reasons I don't sell my articles often as they take days and not hours to complete to my own satisfaction. I think one of the things that has helped me most with this issue is to turn a copy of the content over to the buyer before fully finished (but at a very good stage, not rough draft) to allow them to inspect and make sure it's what they want. You might be surprised how many times you will think you are going in the right direction and only to find out that your buyer had something else in mind. Alternately, they might like your current copy just as well with no revisions! It always helps to have another point of view on your writing, or at least that's what I've found.
Please talk to me about how you deal with this issue; if you over-analyze your writing or critique endlessly and if so how you deal with it so you can move on and produce a finished written piece for your buyer.