While quality content is nice, I actually disagree with the "write it and they will come" approach. Lots of bloggers write great posts in obscurity because they don't explicitly work on the SEO component. Great content is only great for SEO if you take a lot of steps to promote it and use it to get links.
Of course, great content make all your link building efforts better since people would rather link to a quality site. But it's definitely only step one.
To answer the original question, here are a few:
*Directory submissions to the top general directories and to the best, highly related niche directories
*Have an active social media campaign, including G+, Twitter, Facebook, Pinterest, and any other major platforms. Some of these provide links themselves, others are good for promoting that great content.
*Find sites likely to link to you based on co-citation research, and then send them direct, well crafted link requests.
*Guest blogging on relevant blogs
*Write great content and link bait and then promote it like crazy.
Contents plus links should be used to improve rankings of websites on major search engines. The fact is that each of these without the other one may not generate the expected outcome. Even in very light web niches these days, your website needs to have strong packs of links because they will be counted by Google and other search engines, as links are truly internet-based votes sites can get.
On the other hand, if you keep adding tons of new links to your website but fail to recognize this essential need that at the end of the day, when people come to your site, they would look for text materials and contents, your site will not have superb chances of defeating the competitors, winning sales and being recognized as a top portal. A nicely balanced combination of links and contents will be great.
White hat technique is a term used in SEO field means when you optimize a website to rank higher in google search results you do perform some activities, these activities will be genuine and shouldn't be violate search engine terms known as white hat techniques.
Content should be the center of your seo strategy. Good content will get you high rankings in the search engines. And you will be rewarded with high ranking and most of all happy customers. Its all about content.