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.
Write regularly; not too often or too rarely. Two to three blogs a week is a good frequency to maintain. Depends on the genre though.
Photos are the most essential part of your blog or post. Take clear pictures on a light background to keep the focus on the product.