First of all let make a difference between free and paid traffic. You have to decide what kind of traffic is the best for you. If you have some money you want to put in your business then paid traffic is the way to go. But be careful because you need to learn some skills in order to set up proper campaign like doing market research and testing everything you do. Facebook ads is a great place to start!
When we speak about free traffic methods you can use commenting to blogs, forums or social media sites. Try to find sites with high volume of traffic and then place your comments there, give people great advices and build relationship with them.
It is surely very wide topic!