It depends what do you need for. What kind of business. Nowadays all is working, it depends on your audience is it a young one. Social Media would be a nice tool for promoting your products there, or SEO for people who are more interested in seeing the product in details, to read reviews and so on. The most effective tool for me is SEO. I collaborate with the
internet marketing san diego team. My niche is to sell sport bikes, so my targeted audience would be people that like cycling or are professional. So, they are more interested to search on Google, introduce the keywords and my website be there.