Even if you have the best intentions, there are some things you should never, ever say.
You don't necessarily need to hew to tradition, but make sure you've thought it through before you respond to news of a loss so that your offerings, verbal and otherwise, are gracious and of service to another who is suffering. It's OK to even say, "I'm at a loss for words," and give a hug or squeeze a hand.
My story may have ended there, had it not been for a head on automobile collision I would have some 20 years later. I passed out on impact and was immediately enveloped by a warm bright light. As I moved towards the light I had the most euphoric feeling of love and inner peace that I had ever experienced.