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.
Choose a template that suits your blog content. It not only adds to the blog's beauty but will also accentuate the content well. Bad design is always a put-off to readers.
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.