An important factor in doing this successfully is the authority enjoyed by the person giving the correction, or his love - and this love must be perceived. Lacking either of these, the correction will be ineffective; there will be no amendment. Hence correcting others is not for everyone.
Let me rewind St. Ignatius's words: Correcting others isn't for everyone, because it isn't always effective, because the one being corrected doesn't always perceive the love and grant the authority of the corrector.
If the correction will be ineffective, don't do it. You can't get much more effect-oriented than that.
I see many, many attempts at correction that appear to be cause-oriented, along the lines of, "But what that guy's doing is wrong! I've got to say something!" That's a mechanical response, and humans (as reason and faith together proclaim) are more than machines. If the effect you want is to release the emotions what that guy's doing causes in you, then go into a deserted place and reel off an imprecatory psalm or two. If the effect you want is for that guy to stop doing something wrong, then first ask yourself whether he will acknowledge your authority and perceive your love if you say something to him.
See how subjective this is? It's all well and good if you act out of love, but if he can't see that, it won't do any good. And since love is desire for another's good, acting in a such a way that he can't perceive your love may well not be acting out of love after all.
But even if I have a friend who I know is willing to accept correction from me, I still need to be very careful about correcting him. If he is very sensitive to mockery, for example, then I shouldn't use mockery while correcting him. If his eyes glaze over at the sight of a syllogism, then I shouldn't use syllogisms.
Put this way, it sounds obvious, but in practice I find it's hard not to leave it up to others to find the love in the way I express myself. That, of course, is to put love of myself ahead of love of others, and who would fault the other for not doing the work to perceive my love for him buried under my love for myself?