One of the most important factors for a large number of visitors to any website is: backlinks. The more (good!) links show to your website from other website the more visitors you will get from search engines like Google. It is important that the links come from reliable domains, sites and pages and that the sites are RELEVANT to your site. Otherwise search engines could even penalize your site in the search engine results if you have a large number of incoming links from not related sites. That means you should not add links in forums and blogs that are not related to your site.
The best method is to write good and useful contents because people will like good contents at social media site like Facebook, Twitter, Instagram, Pinterest, Google Plus and others. Contents will contain useful keywords so that search engine will index these contents and list them in their results lists.
If you add your website to directories like Multimeta Directory you will also get relevant backlinks because your site will be added to special categories and subcategories that are VERY related to your site. This will help not only to improve the general exposure of your website but offers also additional use for all visitors of the directory. They browse through the directory to the right categories and subcategories or search their for keywords that are important for them.
Each submission means a relevant backlink to your site that will considered by search engines. In the following image you can watch the advantage of directory submission vs. Pay per Click campaigns: