How do you decide whether it is worth it to submit to a directory or not?
1. First and foremost factor is caching date of the page where your link appears. Are search engines crawling and indexing the listing page frequently? If they are not then there is not much point in submitting to the directory. To check caching in Google
A plain HTML link should like this
3. The site should have a page rank(PR). Ideally the page where your site is going to get listed should have a PR
Use a FireFox addon like SEOQuake to check page rank. For bulk page rank checking use a tool like Scrapebox
4. Quality of links in the directory. Are the listed sites of good quality
Good luck with your directory submissions.
If you need any help with directory submissions or SEO efforts please feel free to get in touch. We are keen to help you.