What I am about to say is going to sound incredibly obvious, but it can make the difference between your business being taken seriously, or not.

Edit your newsletter thoroughly.

The biggest mistake you can make with a newsletter is to rush it. Unlike a blog post, or a Facebook status, once a newsletter has been sent out into the world, there is very little you can do to edit it.

Most email marketing servers should give you the option to not only preview your newsletter, but also send test emails. I urge you to use this, send it not just to yourself, but to colleagues or friends using a different mailbox. View it on your phone or tablet. Print it out. See how much it changes in each of these versions, and adapt your newsletter accordingly.

Imagine receiving a newsletter from a business with one or two typos in the content. Typos are easy enough to make, and forgiveable in many situations. However, having typos in your newsletter makes it clear that you haven't put in enough time into it, and worst, that you are not taking your readership seriously.

This isn't the only way you can make your business look less professional, other missteps include:

• Using a personal email address (such as bieber4eva@luvlife.net) instead of a professional one.
• Sending out emails too often.
• Having dead or broken links
• Including pixelated or grainy images
• Using a misleading subject line

Here's an infographic I made earlier with a few more tips to improve your newsletter.