The Best traffic Source are:
Search Engine Optimization(SEO)
Social Media Optimization(SMO)
Google Adwords
Email Marketing

Yes, I agree with you.

Google is the best traffic source
Paid traffic source
Social media site and utube site
one of the easiest was to start building links to your site is to utilize website directories

The best traffic source is Google

Google is the best source to help you gain traffic for your website