Keep your keyword list up to date. Keywords are the building blocks for all optimization efforts on your site. It is important to revisit this list at least once a year to cut irrelevant terms and add in new terms that you should be focusing new content on within your website. There are several free public tools such as Wordtracker and Google AdWords tools that you can use in order to expand your current keyword set, and obtain information on relevance and search volume. Once you have identified high traffic terms, incorporate those keywords into the top level pages of your website for maximum exposure.
Continually freshen web copy. Stale and outdated content can be unattractive for both users and search engines. In fact, search engines “reward” sites for having content that is fresh and frequently updated. When writing new content, have enough body copy on each top level page to support proper keyword phrase density: strive to include the primary keyword phrase approximately 5 times. And don’t forget that including the phrase in your URL and meta data are great ways to strengthen your pages relevancy for search. This task should be tackled at least once a year after you update your keyword list.
Do your own site crawl. Depending on the size of your website and how frequently the content changes, removing old pages and adding new ones to your sitemap file can be a tedious task. To make sure old pages are removed and new pages get proper visibility, perform a site crawl monthly and add important or top-level pages on your website to your sitemap. The crawl can be performed by pulling pages off your server, or for smaller websites, simply clicking through the site to get to the lowest level pages possible. In addition to updating the sitemap file on your site, create an XML sitemap file and submit it to the search engines monthly.
Fix broken links. Broken links not only have usability implications, but they can also negatively affect your brand by causing a poor user experience, especially when they reference old articles that were taken down, or products that no longer exist. Given that, it is important to have proper redirects in place to functional pages, and old pages removed from the site completely. In order to stay on top of this important task, schedule regular website maintenance at least once a month to fix any broken links on an ongoing basis, and ensure that you have a strong 404 page in place that provides a user with an easy way back into the website when they encounter a broken link.
Do regular traffic analysis. You probably look at your analytics on a monthly basis to understand where your external traffic is coming from. But when is the last time you examined other metrics such as top entry pages, time spent on the site, or bounce rate? At the start of each month, look for patterns or anomalies in your analytics data. For instance, if you notice that important high-level or product pages aren’t performing as you would like, try altering different variables on the page, such as content and call to action.
My take/spin on the list:
Keep your language and word usage relevant to your target. The terms and names that get thrown around on a day-to-day basis are in a constant flux. Stay on top of it. What are users seeking? What do they want? How are they going about looking for this content?
Never let your site grow stale. Keep it updated. And not just in the form of a blog. All of your website content matters in the long run.
Personally I wouldn’t obsess over keyword density, but make sure the content reinforces the titles which reinforces the subject which, of course, is based on whatever you’re targeting. (See where I’m going with this?) There’s no magic number, and you have more important things to worry about.
Run regular maintenance checks. Make sure nothing on your site is broken, missing or out-of-date. This also ties into the broken links bit.
Identify key Analytics metrics and keep track of them. Analytics will help you discover new opportunities and trends on your site, including what pages work – and what pages don’t.
Source: Search Engine Land: 5 Website Tips to Keep Your Branding Fresh