I use blogger, too. It's super easy. You mentioned you signed up for tumblr -- if you're interested in posting mainly photos, short descriptions, links, etc. Tumblr is great. But if you're thinking more of a traditional blog with lots of text (ie, more than a couple of sentences per post) accompanying your photos, I would recommend Blogspot or Wordpress. It really depends on what you want to get out of it. If you want to go deeper into your process and who you are as an artist, I'd say Blogspot or Wordpress but if you are more interested in not saying much and instead attracting people with your photos to bring them to your shop, Tumblr will work well for you.