The higher the page rank of the site linking to you, the higher Google will rank your site. If your looking to be listed in Google’s organic results you have to get sites of importance to link to you. Some people like to have a bunch of random sites link to them by the bulk, but Google caught on to such sites and have updated their algorithm’s to recognize it and give those sites a really low rank. If you want results you have to do it the right way.
One way you can start off is to write quality content, if you write well and provide useful information other sites will link to you “just because” and won’t even ask for a back-link. Another approach is to contact other webmasters and do link exchanges, but only to sites that are worthwhile. If your site is useful like I said before and relevant to the site of the webmaster you are contacting, then you would be surprised how many would agree.
http://all-seo-tip.blogspot.com/2008/02/importance-of-backlinks.html