If i did something wrong, I admit it. There's no sense in denying, it will come out in the end and only make things worse. Second, I personally consider it to be the right thing to admit it.
When confronted with something I haven done, I used to get really angry and all emotional, becase I was oversensitive on these matters. Now, i just try to stay calm. First of all, showing a wild range of emotions just heatens the other up. Staying calm can do the same, but the other will cool down much sooner if you stay calm. Short sentences, no long explanations, but overall staying calm.