Site should be simple, easy to read, easy to move around. To decrease bounce rate site content should be of good quality, site design should be attractive, there should not be poor navigation, load time should be faster.
another tip is to know what your competitor is doing for his traffic.......you do the same and add little extra for your traffic.... the bounce rate varies based on niches.
Bounce rate is all about quality content + targeted visitors. Basically, if a visitor is interested in the product/service/information your site offers (targeted visitor), and your site provides what they need in a clear, easily understandable, and affordable way (quality content), people will stay on your site - and your bounce rate will go down.