Be careful with block and other elements! For example, anchor (<a>) will bug if we try to insert a title into it (because it is block).
Watch out for line-height: 0 - it breaks things - for example with images (you can use display: block to remove spaces), and outlook uses percentages instead of a factor for line-height.
Images - use display: block;
Background image - should work everywhere
<table class="" width="640" cellpadding="0" cellspacing="0" border="0" style="width:640px">
<tr>
<td class="" valign="top" height="300" background="http://media.lt02.net/1/Users/28501/Emmet/background.jpg" style="height:300px; background-image:url('http://media.lt02.net/1/Users/28501/Emmet/background.jpg'); background-repeat:no-repeat; background-position:center;">
<!--[if gte mso 9]>
<v:image xmlns:v="urn:schemas-microsoft-com:vml" id="theImage" style="behavior: url(#default#VML); display: inline-block; position: absolute; width: 640px; height: 300px; top: 0; left: 0; border: 0; z-index: 1;" src="http://media.lt02.net/1/Users/28501/Emmet/background.jpg" />
<v:rect xmlns:v="urn:schemas-microsoft-com:vml" fill="true" stroke="false" style="display: inline-block; position: absolute; width: 640px; height: 300px; top: 0; left: 0; border: 0; z-index: 2;">
<v:fill opacity="0%" style="z-index: 1;"/>
<div>
<![endif]-->
<!-- Containing Table -->
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
<td class="" align="center" valign="middle" height="300" style="height:300px">
<!-- Contents -->
<!-- Headline -->
<table width="100%" align="center" cellpadding="0" cellspacing="0" border="0">
<tr>
<td class="" style="font-family:Arial, Helvetica, sans-serif; font-size:24px; color:#fff; text-align:center; font-weight:bold; padding:30px 0; text-transform:uppercase;">And So My Watch Begins</td>
</tr>
</table>
<!-- Headline END -->
<!-- Button - CTA -->
<table class="" align="center" cellpadding="0" cellspacing="0" border="0">
<tr>
<td class="" height="50" align="center" bgcolor="#1a171b" style="font-family:Arial, Helvetica, sans-serif; font-size:14px;height:50px"><a href="#" title="JOIN THE WATCH" target="_blank" class="" style="color:#ffffff; text-decoration:none; display:inline-block; white-space:nowrap; padding:15px; background-color: #1a171b; border:1px solid #1a171b; box-sizing: border-box; -moz-box-sizing: border-box; -webkit-box-sizing: border-box;"><strong style="font-weight:normal">JOIN THE WATCH</strong></a>
</td>
</tr>
</table>
<!-- Button - CTA -->
<!-- Contents END -->
</td>
</tr>
</table>
<!-- Containing Table END-->
<!--[if gte mso 9]>
</div></v:fill></v:rect><![endif]-->
</td>
</tr>
</table>