• Don't stuff your alt tags. In the past, people used to hide content in image alt tags, so you could hover over a picture and get a paragraph or an extended list of keywords separated by commas. The alt text should describe the image, or simply parrot any words that are embedded in it.

• If your site was built a few years ago, or you had work done on it in the past, you should check all of your alt tags to ensure that they aren't spammy or inaccurate.

• Alt tag content should be original. If you have multiple tags with the same content, it should be changed, or perhaps deleted from less important images.

• If your navigation uses images instead of text, there should be alt tags matching each image. Ideally, you may want to consider using text for navigation in the future.

• Not every image needs alt text, especially if you use graphical elements to build a page. You might confuse the search engine if you have tags like "rounded upper right corner" and "tracking pixel."

• Whenever possible, don't exclude your images directory in the robots.txt file. The alt tag describes the image, and services like Google Image Search use this information to put you in results that may be seen in various places, including the top of a general search query. There are people who make quite a bit of money by having products listed in image search.

• If the image is of a product, include the brand name and part number in the alt tag.

• Alt text does not have to be as complex as Wikipedia makes it, but it should still adequately describe the image, using a selection of relevant keywords.

• Use proper punctuation and sentence structure for longer tags. Sales messages ("Buy now and receive FREE SHIPPING") usually are not recommended in alt text. Most people won't see it, and search engines may downgrade your page for being spammy.

• If your image is linked, then the alt text of the image serves as a version of anchor text, which defines the link. For instance, your company logo may link back to the homepage, so your alt text should be relevant to your home page keywords. Note that if you have an alt tag that is relevant to your current page, and are linking the image somewhere else, you may be diminishing your page's relevance. In this case the alt tag should be rewritten to match the target page's topic.