Track each step of the Magento onepage checkout in Google Analytics with this simple Javascript addition to [package]/[theme]/template/checkout/onepage.phtml just add it to the bottom of that file and follow up by configuring with Google Analytics goals

onepage.phtml

<script type="text/javascript">
  Checkout.prototype.gotoSection = Checkout.prototype.gotoSection.wrap(function(parentMethod, section, reloadProgressBlock) {

    // Call parent method.
    parentMethod(section, reloadProgressBlock);

    var _gaq = _gaq || [];

    try {
      // push current checkout section to google analytics if available.
      _gaq.push(['_trackPageview', '<?php echo $this->getUrl('checkout/onepage'); ?>' + section + '/']);
    } catch(err) {
      // silent fail.
    }
  });
</script>

There is a full blog post write up http://ashsmith.io/2012/03/tracking-magentos-onepage-checkout-steps-in-google-analytics/

This includes how to set up your goals within Google Analytics.

There was a typo on line 4 as pointed out in the comments on the blog post, typo has now been fixed :)

Updated to be more upgrade friendly

There's a missing <?php in Line #11 before "getUrl…"

don't forget the echo after <?php