Some writers have a similar goal, making their prose a window through which you see the story. They try to draw people into the story, doing their best to make readers forget they're even holding a book.
Blog design should be the same way. Think for a moment about what the most important part of your blog is. That's right! The posts! As you make design decisions about your blog, ask yourself if the change you're making will enhance or detract from your posts. Here are a few bad examples:
I know people really want an awesome header, and sometimes it takes room to pack in all the awesomeness. Just remember that after the first few times people visit your blog, the header won't dazzle them as much and they'll really want to get to your posts. Headers that push posts down make it harder for readers to get to what matters most.
This principle should be followed in moderation. Headers can also be so anemic that they lose all character. I'm not saying that you can't have fun with your header.
I like a good transparency as well as the next person, but I can tell a bad design when the background is swimming in and out of the text. A background design behind text is almost never a good idea. If you do go for it, be sure to fade it waaaaay back. Don't muddy the water so it's hard to read your posts.
Other ConsiderationsYou might also want to consider the width for your main column. Too wide, and the eye gets tired. Too narrow, and the posts no longer seem to be the main event. Pick out a few blogs where your eyes feel comfortable reading the text and try to imitate what they're doing well.
Don't pick wacky fonts that are harder to read. Stick with the tried and true. Make sure your text is big enough on modern screen resolutions.
Text likes to breathe a little bit. Proper leading can make reading a paragraph much more pleasant.
That's all for now. If you have any questions, or would like me to offer a quick critique on your blog design, feel free to leave a comment, or contact me on facebook.