Formatting - Your post need not be a circus. If you are not good with formatting, then stick to a theme that is light and descent in colors and the post layout. If you are good with trying new stuff then use that skill to better express through colors, fonts and layouts. Avoid colors that are dark and fonts that are overtly bright.
Blogging is a great way to interact with your readers but please avoid the SMS Lingo white creating your content.
Presentation is as important as good content. Have attractive pictures, fonts, etc. on your blog to hook the reader.