In most cases I stick with two primary ways of getting traffic - whichever ways are most efficient and most effective for me.
For example, if I am promoting an information based authority site/blog where the site shares information about a specific topic, then I will typically promote it using SEO and referrals. So most of the traffic comes from Google. The rest of the traffic usually comes from a wide variety of websites such as Facebook, Twitter, guest blog posts, white hat links earned from other sources (usually blogs and forums) or links from whatever forums I promoted the site on. With Google, the traffic will be concentrated mostly on a handful of shorter keywords along with a large number of long tail phrases associated with those shorter keywords.
So even though I am focused on getting traffic using 2 methods, the traffic usually comes from a wide variety of other sources. Most of the traffic will come from one source, usually Google organic search. And then the rest is trickle traffic from a wide variety of sources.
If I am promoting a business, I typically use a combination of SEO and PPC (usually Google Adwords). In that case, the vast majority of the traffic comes from Google. If that works well, I typically won't use other methods. If it doesn't work well, I will explore other options like banner advertising on relevant websites or content marketing of some kind or a combination of content marketing with Facebook ads or whatever else I can come up with for that situation. Most of the time though, the SEO and PPC work very well.