I've created a cheat sheet for Joomla 1.5 templates. Soon to be available on a nice printable page.
Include a Module:
<jdoc:include type="modules" name="theName" />
Display the main content or component
<jdoc:include type="component" />
Display Breadcrumbs
<jdoc:include type="module" name="breadcrumbs" /> //Use the following for 1.6 <jdoc:include type="modules" name="breadcrumb" />
Live site Name
<?php echo $mainframe->getCfg('sitename');?>
Administrators Email
<?php echo $mainframe->getCfg('mailfrom');?>
Current template directory is
<?php echo $this->template?> directory
The live site URL
<?php echo $mainframe->getCfg('live_site');?>
This is how I created a path to my tpl directory, it had to be in the header.
$tpl_path = JURI::base() . "templates/" . $this->template . "/";
The above are good tricks, also checkout Joomla Docs.