DO read a few posts from the blog before you send something. You run the best chance of having your post published if it resembles what they typically run. Things to pay particular attention to include word count, reading level (beginner vs. advanced), and voice (serious, kooky, snarky, etc.). If the blog publishes guest posting guidelines, read them (duh).
DO establish a relationship before you write. This isn’t strictly necessary, but if you’re trying to get a guest post published on a more exclusive blog, you’ll have better luck if the editors already have some familiarity with you. You could start by commenting on the blog, linking to the blog from your own, or engaging with the editors/writers on Twitter.
DON’T write a post that already exists 500 times over. Don’t send a guest post so basic and familiar that everyone has already seen it or could find a SERP full of the same information with a simple Google search. (You know what I’m talking about; we’ve all seen the “Five Ways to Get More Blog Traffic” post.) First, you don’t want to bore the editor of the blog you’re reaching out to, or their readers. Secondly, essentially duplicating a familiar article is a bad SEO practice. Choosing a topic is like choosing a keyword – you’re aiming for something that has volume, but not so much volume you’ll get lost in the noise.
DO write a strong title that matches the content. Sometimes we get guest post submissions that don’t live up to the promise of the title. For example, don’t submit a post called “How Much Time Should You Invest in Keyword Research Per Week?” and then write about why and how to do local keyword research. (Yes, this just happened.) In my experience, a good title that clearly communicates what a blog post offers – along with some well-placed subheads – can make a post 50% better without even changing the content.
DO send an image or two so the blog editor doesn’t have to find one herself. If you’re reviewing a software tool or writing a list of your favorite plug-ins, include a screenshot. If you’re writing a case study, include a table or graph to illustrate your data.