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.
Audience quest: Pay attention to what your audience is asking and give them what they are looking for in your blog. Whether it is content or questions, make it interesting.
Keep your posts simple! Do not try to impress anyone. be yourself! Visit other blogs which might interest you, take part in conversations or simply put your two cents for others to read and follow you back to your blog.