Any content your audience will find useful or interesting you can use when writing a newsletter.
Consider your relationship with your customer when you send them a newsletter. If you run a local restaurant, then cookbook reviews, recipes, some trivia and some news about the restaurant is could easily fill a month’s newsletter. Then throw in a monthly special; ‘only for newsletter subscribers’ and you are done.
Keep your newsletter short. Write short articles, short sentences and short paragraphs. It is okay to produce a monthly 2 or 4 page newsletter and mail it monthly. It will do more good to you than an 8 page newsletter sent quarterly. Your customers are busy and have no more than 10 minutes to sit down and read it. Otherwise your newsletter will end up on the later pile and never get read. Wasting all that good writing.
Finally, no more than 25% of a newsletter should be about your products and services. Nobody is as interested in your products as you are. If they are, create a Subscription Newsletter and charge them for all of that useful content. If you are going to divulge all your business secrets why not make money at it? And if nobody buys a subscription you’ve learnt a valuable lesson – nobody is as interested in your business as you think they are.
That is my quick advice on writing a newsletter and make it useful to your reader while building a relationship with them. That is my quick guide on how to write a newsletter.