Even as a professional writer (or I guess...especially as a freelance writer) I do a lot of proofreading. While many people wonder how reading over their own content will help them improve, proofreading is essential.
Proofreading allows you to solidify your content and your main points. Whenever I work on client articles, I write the entire thing, then proofread, and then I go back and add in optimized keywords, persuasive language, etc. etc.
The same process should be used when writing blog posts, to get them at their best. Ideally, you should treat the first version of your post as a draft, wait a day, and then spice it up into a publishable form.
Do you proofread? What is your take on the process?