Once in your lifetime you might have to provide feedback for others work, how do you do that. Do you just bring out negative and ask the person to change it, or you just point out the positive and leave the negative. Or do you point out both equally.
Though pointing out both is good, as you need to bring out best from that person and you want him to improve. This is where Constructive Criticism can play its role where you have a set of instructions that aims to improve the overall quality by bringing out the negative aspect without upsetting the other person. Constrictive Criticism often contains helpful and specific suggestions for positive change you would like to see rather than providing the general feedback what is good and what is bad.
One way of writing constructive criticism comments is making a sandwich of positive improvement and then again positive. In that way you are pointing out the positive along with some improvement which will not make the person receiving feedback upset.
You also need to provide recommendations on how to improve. Now recommendations are personal preference, it doesn't applies always but it's good to give.