Don't be the kind of brand or company that has a clustered newsletter, even worse a boring-ly designed one! 

Your content may be top-class but if it isn't eye catching, no one's going to read it! Layout your content to be engaging, informative, and easy-to-read.

It also important to remember that you shouldn't overcrowd your newsletter. Try to use graphics or animation that support your content (but not too much).

Your content is the driving force of your email marketing campaigns, It would be best if you plan out what you'll include in your newsletters before you send them out.

Use different data -- demographic, behavioral, transactional, and customer preferences -- using data analytics to understand and segment your subscribers to send them newsletters with relevant content.

Have you thought about how often you'll be sending out newsletters to your subcribers without overwhelming them? If you badger your subcribers with tens of emails out of the blue it will instill a negative experience within them which will make them want to unsubscribe.

However, if you maintain consistency and frequency of sending out newsletters, subscribers are more likely to be anticipating.

The last thing that you should be wary of is at what point of the day are you going to send the newsletter. With over 250 billion emails being sent daily, it's a likely possibility that your email will get lost in their inbox. 

Study up on which certain times and days of the week are users more active.