I believe that social media marketing is important because nowadays, literally almost everybody has a Twitter account, Facebook account, YouTube account. I believe that they are very easy to get familiar with, and when used in the correct way, very effective.
And it is very important to market yourself because on the internet, there are a humongous amount of people and unless you know who you are and what you are good at, you will become just one of the millions of anonymous people.
To build your own brand online, I believe that you need to be able to promote yourself in a way not many other people are doing. It would be best to do something that is completely new. In order to be able to do that, you need to have a very broad view on the net, and sensible to all the smallest trends. I feel it is not an easy task, but it is very challenging and I find it very interesting.