It's not possible to predict exact weightage of a link. A do-follow link from a quality site related to your niche, with not soo many outgoing links, is what I try to get. Sometimes it requires a guest post to get it, and other times a simple comment.
This is the most effective method that I've been using for years with good success and I usually shoot for some competitive terms such as "buy viagra", "mesothelioma cures", "personal injury lawyer", etc. I see one newbie mentioned that even with blogging, you have to get links to those blogs. Well, wordpress.com blogs have tag clouds which link to other wordpress.com blogs similarly tagged. Instant PR to your new blog!!! wordpress.com is not the only one. Some of you need to get out more. Bompa
You can get a good quantity of backlinks if you submit your blog to the top 100 blog directories of 2009.
1. SEO your blog before you proceed further with SEM 2. Claim your blog at technorati 3. Contribute your idea with other bloggers ( blog comment ) 4. Create a few accounts with high authority sites, use their blog function ( example http://youranchortext.blog.friendster.com/ ) and put your sites as blogroll ( Dofollow link ). Bookmark your profile page. 5. Submit unique articles to quality article directories on weekly basis. Hope this help.
Opinion here seem to differ, and I suppose all of the techniques have some pros & cons and all should be used in moderation with importance to blog commenting, social bookmarking etc. But the technique may differ if you are link building for traffic and if you are link building for PR. For PR all of the above mentioned methods are good and for traffic forum posting can be good.
blog comments, forum posting, link exchange, social bookmarks, directory submissions. Hopes It will help you.
forum posting and blogging as well bookmarking can be good way, now a days micro blogging is also a good way
I will suggest to use forums and blog to get more backlinks. Digitalforum is the best forum I know - and wordpress is the best blog where you can start building links.