I agree with what
@cwvps said.
Here is what I usually do:
Right at the beginning when I am first launching the website, I will select one or more keywords to target with the homepage using SEO. And I will also select up to a handful of other pages that I intend to create that I will be targeting with SEO. That way I can build the site out with those goals in mind.
Then when I go to build the site I:
1) Make the site as useful as possible so that people are glad they have found my site
2) Create internal links within the site to maximize the use of whatever PageRank my site ends up acquiring
3) Get a handful of links from various places pointing back at the site so it can start ranking
4) Start promoting the website at a few key places that I have identified as being good prospects for where that site's target audience is spending time online
5) Implement any other promotional methods that I decided would be worthwhile to test
6) Wait to see where it settles into the search results before I begin any serious link building or before doing any major keyword specific off page SEO work
I generally don't bother promoting a website very much using social media at all. The reason for that is because, in my experience, you have to stay active in social media for it to be effective. You have to actively build relationships with people on the social media channels. You have to start conversations with them and then go back and forth with them in conversation for a while. And once you do enough of that, it starts gaining momentum. But that takes a while to happen. And then it takes continuous maintenance to keep that going. If you stop participating in that social media channel, then your followers quit paying attention to you. You lose that traffic source. Social media just requires too much of a continuous presence for me to bother with it.
When I create sites, I want the traffic to those sites to be passive traffic that comes in even when I am away from that website for months at a time. Social media traffic isn't passive traffic. You have to work at getting it all the time unless you are extremely well known in your niche/industry.
