You have to provide a working website which respects TOS and you'll be accepted. what is your website you want to obtain adsense with?
Did they give any reason why your application was rejected? Most common is usually there is not enough content on the site and once you add more, apply again and I'm sure it will be accepted. Oh yeah, another thing... make sure it's has nothing to do with adults or multi-level marketing which is against the TOS.
I will suggest you t set up one blogger(blogspot) and apply for thr adsense. This is the easiest way to get approved. Then, you can use the adsense code in your current website as well
Apply using any other site (not directory) or blog. After they accept your application you can add adsense ads at your directory too. If you have general directory then there is no meaning adding adsense on that (my own experience). DON.