What is a Blog indeed?!!

So someone just contacted me (thanks Justin) to let me know that my RSS feed was rendering nastily; fonts, colours (note Australian spelling), sizes etc... I just checked out my feed and sure enough there were all types of nasty extraneous HTML tags in there - which I removed by hand in the HTML post edit view (arrrgh painful). So how can I make my posts look better without horking up the RSS feed? Or is that not what blogging is all about? I have all of these sexy formatting options in my post editor but it seems that I can't use them for fear of breaching blog-etitic (if there is such a thing).

So if I promise to blog out decent content, could someone help me to make my posts look pretty whilst still being a good blogizen?