If they publish an ezine, subscribe. It will trigger lots of good ideas for your own, If articles are included, and you like something you read, write to the author and ask permission to reprint it. They always say yes because readers will see the reference box included, the author's way of advertising. While an ezine of reprints won't fly, including one or two in each issue works very well. A reader who has read it before, just jumps down to the next item.
Regards reprints, here's a useful trick.
Collect articles you like to a file by date. When you need something for your current newsletter, go back a couple of months. This avoids the problem of the same article appearing at almost the same time in several ezines. Article libraries are a great source for good material. Here are a couple.