A directory depends on humans for its listings. You submit a short description to the directory for your entire site, or editors write one for the sites that they review. A search looks for matches only in the descriptions submitted. Changing your web pages has no effect on the listing. Things that are useful for improving a listing with a search engine have nothing to do with improving a listing in a directory.
Some search engines maintain as associated directory.
Being included in a search engine's directory is usually a combination of luck and quality. Reviewers often keep an eye on sites submitted to announcement places, then choose to add those that look appealing. First is the spider, also called the crawler. The spider visits a web page, reads it, and then follows links to other pages within the site. The spider returns to the site on a regular basis, such as every month or two, to look for changes.