Selling Art, DIY, crafts, etc online

I want to make a post about selling stuff online because quite frankly, I want to start doing it but I don't know where to begin. I've heard about using social media (facebook, twitter, etc.) making your own website and using other websites (such as etsy) but I want to hear what you all think. Is anyone already doing it? Or thinking about it? Or maybe an online marketing guru?

Any and all advice is welcome and hopefully a few of y'all can help out the cause! I'm sure there's quite of few other folks on here who have wondered the same thing because I'm sure everyone can use some extra scrilla.