Zagdoc posted a good algorithim on how to tackle the heart sounds- so I can almost always answer murmurs from the stem. After reading his post it seemed so intuitive but I guess I've never stepped back to look at the big picture. Besides that, I dunno. Practce questions?
There's an iPhone app called "imurmur" that's pretty cool. Has all the murmurs, plus you can switch between the murmur and normal to compare. Also has quiz mode so you can test yourself.