I would like to share my experience with you guys,
Following are some pointers, which can help you to build links effectively.
1) Analyze your top 3 competitors for a particular keyword phrase. Get an average backlink count of top 3 websites, what ever the backlink count is that many links you have to build in next four months for that particular site or page.( This doesn't apply for highly competitive keyword phrases like "Weight Loss", "Web hosting", "Credit Repair" etc. you have to give a longer period of time for these)
2) At first start slow, use unique and informative articles to submit to top 5 articles directories.
3) Then do some 15 - 20 bookmarks in a month. Remember less is more when it comes to google.
4) Find some high traffic blogs and do some blog commenting, don't hesitate to comment on nofollow blogs. These links do have weight for ranking as far as my experience is concerned. This is a bit controversial statement, but if you think rationally, when it comes to natural looking links it's very much possible that you might have 10%-20% links, which come from nofollow page.
5) Then use Web.2.0. Sites like squidoo, wetpaint, hubpages etc. here you have to build in-content links. You can use the re-written version of your articles, which are submitted to article directories.
6) Then use Social Networking sites, leave a link at your profile page.
7) After creating Web2.0 Sites and Social Networking profile pages build couple links to these pages, it might be anything from social bookmaking to answer sites.
8) At this point you will find some traffic is coming to your site from google. Once you find some visitors are coming in from google, then start using niche specific forums and answer sites with useful posts.
9) Scale this campaign bigger as per your link building goal.
10) Start slowly for first month, increase speed in second and third month and for fourth month onward build slow but quality links.
For on keyword phrase I had successfully outranked 1,740,000 competitive pages and grabbed a solid 2 position in google with this link building technique. (Result for my best link building campaign so far)
Note: Do serious keyword research first before starting a link building campaign else it will waste your efforts.