Don’t try to build it like it’s a web page
Using CSS layouts that use external style sheets will make your email look fantastic in your browser, but many popular email clients do not support a lot of basic CSS tags. Sometimes something as simple as using a background image in your layout might not work out if you send it without testing.
Don’t assume that everyone looks at your message full screen on a large display.
Try to keep in mind when you are building your campaign that not everyone is viewing your email with their whole screen. Many people do not actually “open” their emails and instead view them through the preview pane. Ensure that your email displays well in the limitations of a preview pane when testing it with your email clients.
Don’t write a novel
People who own email addresses usually receive a lot of emails. You need to make sure that your email is not a labour to read and that the contents can be grasped by simply skimming over it briefly.
Don’t use video
Very few email clients support the playback of video. If you want to provide videos to your subscribers, the best method would be to place a link in your email with a visually stimulating image. An animated gif file is the safest method of video content to use. The reason for this is that if the client does not support playback of animated gif files, it will still display the first frame of the animation.
Don’t forget to Review
Even though your browser, operating system and software all have spelling and grammar checks, this does not make it 100% assured to be free of mistakes and errors. Take the time to go through your content and iron out any mistakes you may find. This goes a long way in preventing your email from looking unprofessional.