Certainly the easiest thing is, we try never to praise people for things that are unskillful. That's the most obvious thing. And we try never to blame people for doing skilful actions even if we are jealous or envious. There may be a tendency to blame others when they see others doing beneficial things, just through a sense of jealousy.
Knowing how to use of praise and blame so that it has a beneficial result is difficult at times and has to be used skillfully. Say for instance a parent, it would be important for them to praise their children for beneficial things, to encourage the goodness in them. And this type of praise helps them to develop more confidence in themselves. But also caring enough to blame them when they do unskillful things so that they develop an understanding within themselves of what is skillful and what is not. That's the responsibility of a parent. But it needs to be done without blaming the child, getting it across to the child that they're not blaming the personality, they're just blaming the action. Otherwise the child could develop a lot of doubt about themselves.
The way we praise and the way we blame may be very important to look at so the people we are praising and blaming understand that we're not freezing them into a solid type of person that is useless. Or blaming in a way that they develop a lack of confidence in themselves. Very difficult at times to do.
And if we have to blame a person, we have to have the courage to be blamed in return because sometimes we're going to get blamed because we blame. But if we have enough compassion and lovingkindness for the person, and if the situation warrants it, this may be the correct thing to do, to try prevent the person going in the wrong way. If we didn't care at all we'd be indifferent to them and not wish to open to the unpleasant feelings involved with this situation.
So whenever we praise and blame, we have to look at our intention for doing this because if our intention is not based in compassion it may be just a cover-up for our aversion. So look at our intentions, be willing to open ourselves to the results. We are responsible for our actions, speech and thoughts. And do not always expect that you're going to get the response that you would prefer.
Sometimes if we don't know the person very well it may be better to just develop equanimity and not take it on ourselves to correct other people's actions. We have to actually see whether the situation we are in warrants that we take on the role of praising and blaming anybody.
There are so many variations to this question that its impossible to probably cover them all this morning.