Zdrastvootye (I don't have a Russian keyboard, or Russian fonts...and pressing a key combo doesn't bring up any Russian letters either )

I'm having major problems understanding when to use a normal possessive and a reflexive. Da, ya znayoo what they MEAN (svoy etc means someone's OWN), however, I know the meaning can vary depending on the context of the sentence. Neither of my books explain this in much detail, and they only give one example each.

Pomoch!!