What are you selling/marketing/trying to do with the e-newsletter?

And: did you get their e-mail addresses correctly? Are you conforming to CAN-SPAM rules? Have they confirmed they want to receive your e-mail? If so, good job....

If I were you, I would NOT send an introductory newsletter e-mail telling them you are going to be sending them e-mail, it's just another step. Just send the e-newsletter.

For your e-newsletter:

A) Repetition:
Develop an ongoing set of sections that you use to interact with your customers, and always re-use that template, so they get used to skimming through and going to their relevant section

Sample Sections of your E-newsletter
i) Intro
ii) More Details about What You Are Offering
iii) Upcoming (e.g. ways to connect, events, book launch)
iv) Call to Action
v) Thank you
vi) PS) (people always like these postscrips)
vii) Unsubscribe information & Contact information

B) Catchy subject line:
Some e-newsletters go straight to delete without me even opening the message, because they're not relevant:

Sample subject lines of emails that go into Trash:
"Connect with CompanyName at UpcomingInternetConference"
"Webinar Coming Up"
"Website Newsletter Update for September"

C) Compete on relevance:
People are bored/tired/stressed/aggravated/on their lunch break. How can you compete? Give them something super meaningful and relevant.

D) What's in it for me:
What benefit, value, bonus, discount, coupon, deal, or behind-the-scenes/members-only information do you have for the recipient? Keep it succinct -- they are giving you their attention, make that count --- put the benefit directly into the first and second paragraphs.

E) Who are you again?:
Remind them about your blog/business with your tagline or memorable slogan, or your photo.

F) About images:
An embedded picture of your product/service may be helpful especially if you have a very visual set of offerings

G) Easy-to-read:
Craft your e-newsletter to be easy-to-read (bolds, italics, bulleted lists, horizontal rules) with ONE specific call to action. Too many options = confusion/inaction/passivity.

H) Action:
Embed a specific call to action. Give them a concrete thing they feel like they can do, e.g. "Purchase by midnight" or "Like us on Facebook"

I) If you already have blog content I wouldn't spend more than a few lines toward the end of your e-newsletter to drive them back to your blog, for example "Check out the latest: Link 1, Link 2, Link 3" where your links are really engaging one-line titles. Some of your readers may already have subscribed to your blog so it's too repetitive to mention your blog posts yet again.