yahoo search engine focus on-page factor, Google focus on content so if your website has on page and content part good then no one can beat you.
All the SEO techniques are important for getting better ranking for the web website in search engines. But a part of all these techniques accepting backlinks absolutely helps to access PR. So try to do social bookmarking, forum posting and link building to get more backlinks for the site.
Backlinking is very important but it should be realistic. A site created a week ago that suddenly has 1000 pages and 15,000 backlinks is unrealistic and will hurt you before it helps.
OO i have been providing lot of good content but couldnt do much with it until i started blasting my sites all over the place.. now i rank good
if you perform each and every techniques then only u will get quality back link and relevant visitor to your site. every techniques is imp. from their point of view. for ex,u r getting back link by link exchange but u r not performing Directory,then u will not rank high in google,though directory has less weight age, but it has to be done.