Before criticizing anything or anyone – how so ever constructive or benign it might be, I would first see inwards.

Could I have done it the way I want it ought to have been done?

If my reply is unconditional yes, then and then only I would gear up to criticize.

Next test: If I am criticized in the same vein, would I be able to take in?

And the last test: Why should I criticize at all?