SEO companies still focussing on this stuff are either scamming people, or just so out of date and it will catch up with them.
Backlinks are still very worthwhile, but they must be earned naturally. Any backlink that can be bought is not natural.
SEO post penguin is actually REALLY straightforward! Implementing it is blody hard, but the theory is straightforward.
Really, all you have to do is create good quality content, relevant to your business on a regular basis. You also need to socialise this, be social on your social networks, publicise your content through your social means, earn backlinks by people coming across your content and deciding to link to it
Ultimately Google wants to know that your site is good quality (and it measures that by deemed good quality sites naturally linking to it because they think it is good). Social signals, tweet, number of facebook likes, google plus ones, other kinds of shares, people talking about your site etc.
Don't focus on 'SEO'. Focus on building a great website, a great brand and getting the word out and the links should come naturally.
Obviously all the on page and technical seo, ste speed etc best practises still apply.