The more back links that point to your web site from highly ranked web sites the better.
Other things that help are an aged domain, a good domain name, good content updated frequently.
I am working with a new program that facilitates creating content with back links.
In addition, it makes it easy to post to multiple places to get your back links out there.
There is a free version. I have the paid version to get all the features.
You can go to http://www.hyprcast.com/invite/?gold with the invite code of GOLD to get the free account.
Once there you can get access to 66 videos that show the features of both the free and the paid accounts.