Hello,
I thought this was a good overview on how to speak with employees in a way that can motivate, encourage and help the indivdual to grow. What I have also found to be effective when speaking with individuals is to have them give their own critique on the situation first. I work in a phone-sales position and when I sit with employees to discuss a call, I will often ask how they felt it went before giving my feedback. I have found that almost always the individual is directly on point with areas of improvement and I act more as a supporter instead of discussing what went wrong. I have also found that if employees critique themselves, they are more likely to improve in that area vs. management trying to work and train with them to correct it.