There are many search engine optimization experts that will defend (to the death) that "content is king." And then you have the guys that say they can use off-site factors only and get a ghost page with no content to rank on the 1st page of "all-mighty Google."
Well, interestingly enough, both of these "experts" are correct...but with some conditions.
Yes, a web page can get ranked very high based on content and on-site SEO alone, but that's only if the competing results are very weak and there's aren't many "players on the field."
Now, on the other hand, a page with weak on-site SEO and no content can get ranked high if it has tons of backlinks and inbound anchor text links, but that's only until the websites in that market with good on-site SEO build a couple of backlinks, then it's all over for "no content sites."
So, it seems like the only logical solution is to first make sure that your content and on-site SEO is pristine, then you really don't need as many inbound links to take high positions. Both content and backlinks are very important, but if you do the content and on-site part better than your competitors then you won't have to work nearly as hard as your competitors to build backlinks.
Here are some pointers for on-site optimization factors:
#1: Keyword in the <TITLE> Tag
#2: Keyword in the URL
#3: Keyword in H1, H2 and H3 Tags
#4: Keyword in the first sentence
#5: Keyword in the LAST sentence
#6: Keyword density of about 2% to 4%
#7: At least ONE outbound link to internal page (another page within your site) with Keyword as anchor text
#8: At least ONE outbound link to REPUTABLE external page (ie: Wikipedia)
#9: Remove all excess, junk, and unrelated outbound links
#10: Add at least 1 image with ALT text set to Keyword
#11: Have bold, italic, and underline of Keywords.
#12: Minimum of 500 words of relevant content.
Having as many of these on-site SEO and content factors in place is going to dramatically increase the effectiveness of your backlinking efforts.