Originally Posted by MarkBrown
The answer to your question is highly dependent on where the target audience for your website/product/service is hanging out...
Yes, you need to know your customer well, and plan your website promotion according to this. For example, if you sell dresses, it makes sense to take great photos of your products and share them on Pinterest. Or maybe your potential customers aren't active on social media and it will be better to focus on SEO.
Find forums, social media groups, blogs related to your website's niche and become active there. This way you'll drive targeted traffic.