Hey, money makers.
The Tumblr(yahoo) updated their policy, they won't let adult blogs to live. The adult blogs won't be shown in search engines, and in tumblr search too. So don't go in that niche.
Try to focus on SFW tumblr niches, you can find it there: http://tumblr.com/explore
So there is a method, for people who earned a bit starter money.
Buy a nice domain, and hosting and install a Wordpress site on it. And drive traffic to it from tumblr.
Use adsense ads, and you will make much! Try to use more tumblr accounts, and Queue, the best if you get 1000-2000 traffic at minimum. With that you could earn money, really.
So get on that wave and make money with tumblr!