How To Create Prefect Email Newsletter?

In my experience the key is to focus on three things. First, you should keep it simple. The more complex your email design, the more likely is it to choke on one of the popular clients with poor standards support. Second, you need to take your coding skills back a good decade. That often means nesting tables, bringing CSS inline and following the coding guidelines I’ll outline below. Finally, you need to test your designs regularly. Just because a template looks nice in Hotmail now, doesn’t mean it will look nice in all email client.
I always use following guidelines as a foundation.
Top 10 tips to design pixel perfect email newsletter.
1. Use tables for layout
2. Set the width in each cell, NOT THE TABLE

<table cellspacing="0" cellpadding="10" border="0">
	<tr>
		<td width="80"></td>
		<td width="280"></td>
	</tr>
</table>

3. Use nested TABLE
Table nesting is far more reliable than setting left and right margins or padding for table cells. If you can achieve the same effect by table nesting, that will always give you the best result across the buggier email clients.
4. Use a container TABLE for BODY background colors and background images
Many email clients ignore background colors specified in your CSS or the tag. To work around this, wrap your entire email with a 100% width table and give that a background color.

<table cellspacing="0" cellpadding="0" border="0" width="100%">
	<tr>
		<td bgcolor=”#000000”>
			Your email code goes here.
		</td>
	</tr>
</table>

5. Always use CSS INLINE
6. Avoid shorthand for fonts and hex notation
7. Avoid Paragraphs, use <br/> tags
8. Always include the dimensions of your image
9. Avoid PNGS
10. Don’t forget alt text

Ref: http://24ways.org/2009/rock-solid-html-emails/