I think, a blogspot sub-domain is better than a newly-registered bad domain name. For a blogspot blog, you don't need to worry much about generating a Google XML Sitemap, where to put Adsense code in the template, just keep on updating. And to my own experience, I give more credits to a Blogspot blog or Wordpress than others. For beginners, sometimes you maybe better to try revenue sharing site, such as Hubpage or Squidoo or this forum, most of my earnings come from hubpage, I have never got any clicks from this forum yet, though.
if you don't have a real domain name (i suppos it's a free hosting) you will not get anything more than $1. In order to make some profit you will need to invest some money first (buy a good domain name and a hosting account)