Updated January 4, 2018.
SEO: Those three little letters stand for "search engine optimization", but there are many different ways to go about it. What SEO means is telling search engines like Google that your site is relevant to your audience. Its importance for your website can't be understated. Avoid these SEO mistakes at all costs.
1. Not doing any Search Engine Optimization at all.
"SEO, who needs it?" you say. "If I build it, they will come." But will they? How will people find your website? Most organizations are online because they would like to reach new people or provide their current audience with information. If you have any plans to attract visitors who might not be familiar with your company or organization yet, then you need to think about your SEO strategy.
2. Never updating your SEO strategy.
If there is one truism about Google's SEO ranking algorithms, it's that "Everything changes." Google is forever working out new algorithms and methods for ranking websites, and some of these changes come at the expense of what were previously the right steps to take in preparing your site's SEO. It's important to stay up to date on the latest advice to help your site rank well. If you don't have the time or inclination for this yourself, ask your trusted web developer to help or to recommend someone who can help you.
3. Targeting keywords that are too broad, or not using long-tail keywords.
Don't try to rank #1 for generic terms like "defense attorney" or "Italian restaurant." You don't need to rank #1 for "Italian restaurant" in Ontario if you're based in Nevada. What makes your organization or company special? If your patrons tend to be local, use that to your advantage by helping people find "defense attorney in Dayton, Ohio" instead of just "defense attorney." Think about what people are looking for when they find your site, and be as specific as possible. Reaching your local audience is key.
4. Using unnatural-sounding text.
You should use your keywords in your content, but not to the extent that your text sounds contrived. Long gone are the days when a so-called "SEO specialist" could put white text on a white background and repeat the keywords a thousand times to get to the top of the rankings. Google can easily spot this practice, called "keyword stuffing," and it can hurt your rankings. These days, Google is looking for natural-sounding copy in your content. If you're trying to use "San Francisco, CA database design" as the keyword-phrase on your page, it's ok to use it where it fits in naturally, but don't just repeat it over and over. Besides the negative effect on your search engine rankings, it makes for awkward reading for your visitor.
5. Not adding or updating content.
Consistently updating and publishing content will help your website rankings. Google's algorithm ranks sites according to recent activity, so if blogging is part of your content strategy, it's important to post new articles on a consistent basis. If your company or organization doesn't lend itself easily to a blog, or you haven't got the time to dedicate to it, you can still go through your webpage content every so often and update it, so that Google can see you are still actively engaging with your website.
6. Worrying more about SEO than about your visitors and their experience.
Just as not doing anything is a rookie SEO mistake, so is making SEO the holy grail to the detriment of your visitors' experience on your site. Your website needs to attract visitors, certainly. But first and foremost, you need to ensure that those visitors will have a good user experience so you can keep them coming back once they've found you.