I intended to highlight two articles regarding copywriting tips. Both contain timely, useful information for writers. Both also have typos of the sort easily caught with careful proofreading.
Rather than link to pieces with typos, I decided to post this obvious bit of advice: Read what you write out loud, as if you're seeing it for the first time.
Another tip: Record yourself reading the article, story, or pitch and listen to it without reading along. Goofs, duplicate words, and weak spots tend to jump out when you do this.
Want to feel (somewhat) better about your typos? Here's a link to The Atlantic's "The Best (Worst?) Typos, Mistakes and Correrctions of 2012." Enjoy!