Make sure you are interacting with your readers! If you are not doing so, your are not blogging.
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.
Offer easy tips for any problem and your readers will return every time they need some advice.