Don't overestimate the time your recipient will spend on your email.
Use design as communication, rather than for design's sake - make it easy for the recipient to skim-read and instantly pinpoint items of interest.
Don't use lengthy news items - include a summary and allow people to click through to your website to read the remainder if they're interested.
Consider the right time to send -will your customers be busy on Monday morning? Will they be in the right frame of mind on Friday afternoon?
Experiment. Split your list into two and compare the response to different wording, designs, or campaigns sent at alternative times of day.
A well-written email with the correct balance of graphics and text and carefully placed links is more likely to reach the intended recipient and deliver your message effectively.