Before you hire one, ask to see past copies of other newsletters they've published. Make sure they have the right attitude to match your visions of what the newsletter should accomplish. To the technically savvy, online newsletters can be a relatively simple task. Talk with your business partner, staff, friends, family, and whoever else will listen about what should go into the newsletter. Brainstorming can be a great way to come up with ideas that you'd never have thought of alone.
Research competing online newsletters to see what they're all about.
If you find there are several newsletters out there pertaining to your biz, try to find a unique niche for yours. Contact your Internet Service Provider for help. Find out how much they charge to do mailing lists. Devise a way for visitors to your website to subscribe to your newsletter. Create and maintain an archive of past and current issues of your newsletter.