Directory Submission is one of the easiest ways to obtain one way links. Though it is easy, but addition of websites in directories needs to be done carefully by checking the home page whether it is google index able or not and choosing an appropriate category for directory submission.

Most of the directories offer two kinds of listings one paid, other free. Though, in most of the cases we go for free listing, but there are some cases when it is beneficial to go for paid listing. I am going to discuss the cases where paid listing can benefit your site ranking.

•   Niche Directory Submission: Niche directories are directories based on a particular theme or contains link based on a particular theme such as travel, Seo and many more. If there are any directories related to your site theme, then it is advisable to go for paid linking since it is related to your site, it will be considered a quality link in terms of google and will really help your site in gaining ranking tremendously.
• Directories with high PR: If directories have some internal page PR, frequently index able by google and do not have more than 30 links in a page, then it is no harm to go for paid listing in a directory.
• Traffic of a directory: If a site attracts decent amount of traffic daily, is related to your them, then you should go for paid linking. Suppose you have a travel related website, then getting a link through travel portal such as lonely planet or trip advisor can really help your site in getting unique traffic.
  

Directory Submission is an important tool in building one way links, though most of the directories are free and we do free directory submission, but if there is a case when we have to shell out money from our pocket to get link through high traffic sites related to our theme, then there is no harm in getting it.