We use some keyphrases for a site and get them ranked for a site.

Some of the ways,where we can use keyphrases are blog commenting,directory submissions,do follow forum posting,article submission,press release submission.

In those ways,which one is more effective to get ranks for a keyphrase?

Or is there any ways which are more effective than the above ways?

I expect to hear views from the people who have experience in the seo field from two or more than two years as they may experience practically.

thanks in advance.