Given that your blog has great content, it should also be presented in an organized way. Link within, smart layer are some must have widgets for the same.
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.
Optimize your WordPress to load quickly. The loading speed of your website directly affects visits and conversions on your website.