A mistake I find often is that Robots.txt with a no follow are active, make sure this is not the case as Google will not be able to view your content on your site, this means no Google rank.
Back-links are tricky! Don't be fooled into web directories as they often have negative results in Google's eye's, this is because the are mostly spam.
What I strongly recommend is joining the main social media websites to start of your back-link building e.g. Google +, Facebook, Twitter, etc.
Another good idea is to ask your favourite blog in the industry your associated with to link to your site, or even better to write a blog post about you and your business.
I hope this small Segment on seo tips helps.