When you pick up a new game, you spend alot of time learning to master its intricacies, a dance I'm long familiar with due to my love of systems and my "Gamer ADD." You try new things, make mistakes, re-read the book, and see things in a completely new light. And then you tell your players, they nod and agree, and life moves on.
World of Darkness is a very flexible, very "narrative" system. The rules function primarily to facilitate your telling of a story. They resolve disputes, tell you what happens next and, most importantly, help create "interesting choices," the very core of "gameplay."
Vampire's frenzy rules work exactly so. They grant me a chance to step into the heads of my players' characters and show them how alien a vampiric state really is. I can reveal how profound a vampire's hunger or rage really is with the roll of a die. However, if I use too heavy a hand, I violate another rule that I must confess I often violate: do not tell the players what they are feeling. There's two good reasons for this. First, it's just bad form. A player is in control of his character (except when he's not, the whole point of frenzy), and knows how that character feels better than I possibly can. Second, more importantly, it's a crutch. If I say "You meet a scary guy. He's scary. You're scared," most players generally dismiss the character. If I show you that he's scary, with words like "looming" and "sinister" and "flashing eyes," then most player characters will understand that fear and react accordingly. (There's a third reason in a vampire game: Vampires often mess with your mind and emotions. "The vampire uses nightmare, therefore, you're scared" creates different results, a different feel, than describing a scary character and letting the player react accordingly).
I think I over-used frenzy in the last game, though much of it was Predator's Taint, something that always occurs. Perhaps my players wouldn't agree: Many of Roomie's frenzies came understandably from his hunger, while other characters (like Byler) hardly needed to roll for frenzy at all, as they were in a well-controlled environment and well-fed. According to the book, it's "up to me" when characters should roll for frenzy, but it shouldn't happen all the time.
The book also repeatedly states that vampires cling to their humanity to stave off the beast (ie frenzy), yet provides no mechanics for this. Thus, I propose a personal guideline: the higher your humanity, the less often I require you to roll for frenzy. Another book (I forget which) offered the idea of rolling a single die and comparing the results to your Humanity. A roll equal to or lower than your Humanity resulted in "virtuous" action, while higher than your Humanity resulted in "sinful" action. The book suggested this as a roleplaying tip, but I think it might serve well as a guide for frenzy: If I am in doubt as to whether or not you should frenzy, I will roll a die and note the above. Thus, Dave is far more likely to frenzy for "little things" than Roomie, thanks to his mounting madness after diablerizing that vampire last session.