Make sure you have some good analytics software installed on your website. You will want to know where your traffic is coming from. Is it coming from social media, referrals, search engine queries, or is it direct traffic? It will also help you determine where people are getting lost, or dropping out of the funnel. It can also help you determine what approaches, content, and CTAs are the most effective.
I still believe that Facebook and Google are great platforms to promote your business, but only if you are willing to pay. If your goal is Organic growth, I recommend looking at newer platforms such as Quora, Reddit, Snapchat, Medium, Instagram, Tumblr and similar. These are all established platforms that still offer some opportunities for organic reach, because although popular, they are nowhere near the saturation levels of Facebook and Google. You can also look at startups that you feel will become very successful in the future, take a small gamble perhaps and try to establish a strong presence there.