Content is important,even the king but without any traffic your website content is useless,you need good search engine rankings if you want traffic and you need good quality backlinks if you want a good position in search engines,indeed link building is a never ending process.
From where i stand commenting on do follow blogs is the fastest and cheapest way to get some incoming links with your desired anchor text,links that you need to improve your organic search results.

Finding dofollow blogs shouldn't be too hard since are plenty of lists and directories if do a little search on Google. You can save some time by seeing my compilation with best dofollow resources and my guide to find dofollow blogs.

Now..before you start you might want to download NoDoFollow Firefox Addon plugin that allows you to see which links are or aren't dofollow.

Blog Commenting

I strongly recommend you to start commenting on blogs related to your niche first and then expand,this will take time but if you want good results you need to have incoming links from as many places as possible.

How To Successfully Comment on a Blog and Get a Permanent Backlink

1. Comments Policy - Not many blog owners have a policy but if they do take your time and read it,it's a shame to get your comments unapproved because you failed to read it.
2. Criticize Kindly - Don't be rude in your comments,even if you don't agree start by pointing out where do you agree.Never personally attack a person or be sarcastic.
3. Keywords Instead of Name - If there is not comments policy and you see other approved comments with keywords instead of names then go for it!
4. Comment Relevance - Write a meaningful comment.Garbage comments like "great article","nice blog","awesome post" will not get approved and if they do you're losing some visitors my friend.Add value with your comment and you will draw attention to your own blog.
5. Links in your Comment - You can link out from your comment to your own article as long as your article provide additional information about the topic or you have a different point of view but be smart and add a short description to your link,for example if the disscusion is about "10 best cities to live in" link out to your own post stating something like this "I have written an article on the same topic but our point of view are very different,i don't think that...you can read more details here" that gives you a important incoming deep link from a related site with your anchor text.
6. Create a List with Related Blogs - Ok, you're done commenting for now,see what blogs gives you good link juice and visitors and go back once in a while,once you begin to be a regular commentator you have a good chance that the owner will link to your articles naturally.

What kind of blogs you need to find?

1. Relevant to your niche with high PageRank. Learn how to increase pagerank.
   
2. Do Follow -NoFollow links don't pass pagerank or anchor text so they are pretty much useless for your rankings but of course those incoming links can get you some traffic.

3. Blogs that have KeywordLuv plugin enabled - KeywordLuv is a plugin that separate your name from your keywords in the link to your website giving you a improved anchor text,all you need to do is to enter in the Name field "Name@YourKeywords" so if your name is Matt and your keywords are "Free Traffic" simply enter "Matt@Free Traffic" in the Name field and your in comment you will have "Matt from Free Traffic Says:".This anchor will get you better search engine results for your chosen keywords.

4. Blogs that have CommentLuv plugin enabled - CommentLuv is a plugin that will attempt to parse your blog feed when you comment and will display your latest blog post at the end of your comment(you can register at CommentLuv.com and choose which post to display).Benefits? A permanent deep link pointing back to your blog and probably a nice amount of new visitors.

How to find KeywordLuv and CommentLuv blogs?

Search Engines are your best friends when comes about finding something that you need.

1. To find KeywordLuv blogs open Google Search and use this search string Marketing & “title=”This site uses KeywordLuv”" or Marketing & “title=”Name@YourKeywords”" to locate blogs with KeywordLuv enabled in "Marketing" niche.Change "marketing" with your own keywords.
   
2. To find CommentLuv use same method but with this search string Marketing & “title=”CommentLuv Enabled”".

Other Useful Resources:

1. The Ultimate Do Follow Blog List with High PageRank
2. List of 100 Blogs Using CommentLuv Plugin
3. My 100 Fresh Blog List of CommentLuv