There's a moment when you're holding something the other person will not want to know. As you wait for them to answer the door, or come into your office or pick up the phone it feels like you're about to hand them an exploding package. A lot of energy is about to be released, you want to be able to absorb it and take it to ground. The key to this is humility and compassion.
Humility will allow you to not know what the news needs beyond the facts. Let the facts be said as gently and plainly as possible and then let the person hearing them cycle through their own meanings as the shock discharges. If someone is losing their job or marriage, humility reminds us that we don't have to spin it as good or bad news. When you are delivering awful news neither disasterize or "bright- side" it. Don't assume that the news is overwhelming or sad - state the truth without fuss.
If someone has died there is no way for you to know what their loved one needs to do with that information - do they need to rush to where the body is? Do they need to collapse onto the floor? Do they need to learn more immediately or do they need to let the sentence settle. Not knowing allows you to respond to what comes up rather than trying to lead or control.
Humility means that you may have your own needs or limitations and you are entitled to them. Have compassion for yourself. You are not some special saint, you are not the only one who can do things and you may or may not be the right person to help here. If they collapse into your arms and you can not hold them, humility lets you guide them to the couch or to someone else. If you are there on a mission, for example if there is an immediate need for information, state your facts or ask your questions.
Turn off empathy, and move into compassion. Empathy is an act of language, story and imagination, compassion is a way of being present. Empathy is useful when we are considering a course of action, compassion is useful when we are doing it. Think about the way a dog or horse would hold space, wordless and concerned. This mindful attention, this resonance is the essence of compassion. If sounds are appropriate, murmur. If words are required, use them to resonate what the other person says. Like this: "I'm shocked...." "...you're shocked..." "It's hard to believe this happened..." "...hard to believe..."
It's particularly important to stay away from empathy if you are uncomfortable. Uncomfortable people tend to chatter and emp
athy gives them something to prattle on about. Don't tell them some story about how you can relate. If they are reeling from bad news the last thing they want is to here how you handled it when your pet frog/Aunt Millie/boyfriend died. Empathy loads your circuits with a mirrored shock wave which makes you unstable and needlessly stresses you - again - turning your attention toward yourself and away from the person who is actually in the middle of the crisis. And it's not even accurate. The person you're breaking the news to is going to go through their way, not your way.
Finally, use the experience as a learning experience. When you have time to reflect, think about what worked and didn't seem to work for you. Practice the alchemy of feeling blessed to be a witness.