How often should I submit my blog to search engines?

Question From User - Answers in Comments.

I have some blogs, and they don't get much traffic. I have submitted them to Submit Express about a month ago. How often should I re submit, and is there anything else I should be doing to get traffic.

I know about face book, twitter, digg, stumble, but if you don't already have lots of friends on line I don't see how you increase the people who see you on these social media.