I am just curious to know about the marketing methods being employed by Tor hidden services .These .onion domain sites cannot be indexed by normal search engines like google etc nor they can be used by browsers of the clearnet like chrome,IE etc. Methods like search engine optimization and other marketing techniques cannot be used either as they aren't part of the clearnet. This dark web section of the internet is beyond reach of almost anyone. Despite all the things I mentioned above,how these hidden services manage to get thousands of members or subscribers? What are the marketing methods these sites employ?
Well there are several ways to advertise an hidden service. Google doesn't index hidden services at the moment, but ahmia.fi does it. So your hidden service might be found this way.
Another possibility is word-of-mouth propaganda. Just offer a service that many people want and news about the service will spread via mails, messages etc.
For non-Tor users there are Tor2web gateways. So you can also have a "normal" web address to attract those users.
You may use Tor ads. http://toradsc6vvmtugty.onion/ ,but stick with indexing your site in Wikis and search engines.