Do social bookmarking, Social Networking and forum posting to increase site traffic. Most important if you can write unique content then create your blog and optimize it on regular basis.
All methods you mentioned depend on your time and should be patient. We can not see the result only one night.
This would be useless if you buy traffic because you are not sure if they are real traffic or not.. And no guarantee that you will make a sale.
Forum posting is one of the best way to bring traffic to your website. You can also do an Article Marketing and Social bookmarking, create unique and quality content for attracting organic traffic from search engines.....