I use Mailchimp.
I started with this because it's what my workshop uses and there was someone there to show me the basics about how to use it.
I'm happy with how it's going...
There are at least two schools of thought regarding how often to send it out.
There's the little and often style, and there's less frequently, but more substantial option.
I think that it really depends on what comes naturally to you.
When I started mine, I knew I wouldn't want to write a newsletter too often (it would become a chore for me), so when I asked people to sign up to it, I explicitly told them that I would only be sending a newsletter out 4 or 5 times a year.
I sent out my 6th newsletter last month
http://eepurl.com/P9feHI have a subscribe button on my website and a signing up form linked on my FaceBook page - but don't ask me how I did that now - I can't remember!
https://www.facebook.com/LynnBaileyPrintmaker/app_100265896690345Would be good to hear what other people's experience of newsletters are...
L