My friend told me that social bookmarking and directories submission techniques don't work to optimize the site. Is there any other alternative of it??? I have also used the tactics of article submission and blog commenting etc.
There are lots of SEO techniques. Have a read through this SEO FAQ:
There's also a lot on Google, too.
I'll close this thread, because the question is too general, and there are already lots of answer available. If you have a more specific question, don't hesitate to ask.