Create a basic blog using a free blog-hosting service like Blogger or WordPress. WordPress also offers blog software you can run on your own site and URL, or you can go for one of the other giants like TypePad or Expression Engine.
Customize your template to fit a futanari theme. Even free software lets you add your personal touches to a blog's design. Your blog will stand out from the herd if you customize it as much as possible.
Find your blogging voice and angle. More readers will visit your blog if you have a unique perspective about futanari, rather than sounding like every other blog out there.
Search out relevant content. Whether you are creating your own futanari art or posting reviews of futanari manga, you need to provide both clever narrative and engaging images. Try to keep the content varied enough that your blog offers a service for those interested in the futanari community.
Post regularly to keep people coming back to your blog. While you may not be able to provide original artwork or amazing scoops (you should if you can), you can still draw readers by offering plenty of new content.
Make your blog a dialogue instead of a monologue by responding to comments. Hopefully, you can answer any questions readers may have about futanari.
Include images. A futanari blog without great futanari won't get very many hits. Be sure to abide by applicable pornography and copyright laws.
Give the audience what it wants. Check your stats to see which posts are read the most and then try to include similar topics in future posts.