Write something useful for yours reader. Share a relevant piece of information, an event update or a hack that makes a task simpler.
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.
People follow bloggers but for better blogging, bloggers should also follow them back.