Rather than randomly critique a sketch or shoot down an idea, the general rule is that you may only criticize an idea if you also add a constructive suggestion. Hence the name plussing.
— Daniel Gogek (2014) Plussing – How Pixar Transforms Critiquing into Creating

Feedback is tricky: seems the easiest thing to do, we do that every day, all the time, and yet doing it well is a skill that has to be learned.

Plussing isn’t something special or something new. There are techniques like “plus delta” and “start stop continue” (check Gamestorming) that use the same principles. These techniques don’t work in isolation, but aggregate together in a system of feedback they all compound to a culture that leads to great solutions.

Notice how the article itself hints at the other aspects of this feedback of culture:

The teams of animators then meet each morning to review their previous day’s work, and critique it.

This is a place where open and daily feedback already happens, and it’s a review done not on complete drafts, but incomplete pieces. So that’s the context where all of this happens.

Also, there’s the reception side, so how do you get feedback. Hints of that too:

Pixar says the practice has been built on the core principles from improvisation, which are: accept all offers (accept the idea, don’t reject it), use “yes, and …” instead of “yes, but …”, and make your partner look good.

Of all the three suggestions above, I’d add a note for “accept all offers” which I know from experience it can be counter intuitive. People try to defend designs, and reject ideas. This isn’t wrong, per sé. It’s worth explaining if something wasn’t clear. However, in the context of the feedback, it’s important to accept the offers. Then you go back to the drawing board, list them all, and evaluate them properly. In the end you might not accept all the ideas. That’s entirely normal and it’s part of your job rejecting some of them. But these are two different moments: there’s the moment you get the feedback, and the moment you evaluate it.

Also interesting that the article moves then on to describe some principles of negotiation (Harvard Negotiation Project), to which one stands out to me as being very important:

One of the core principles is to separate the people from the problem, and thus take the focus off personal issues to avoid negativity.

This might be difficult to absorb because it can be very subtle even just in the way you phrase things. For example saying “The design you did…” is an implicit hint on the person, which triggers defences, even when rationally you both know that’s not the case. It’s unconscious. So the best way to phrase it is instead “That design concept…”. Shift the focus of the feedback from the person to the thing criticized.

In this short article, we get a few principle that can improve a lot your way of giving feedback:

• Criticise only if you can add to the idea, never take away only (plussing).
• Discuss in-progress drafts.
• “Yes and…”
• Make your partner look good.
• Separate the people from the problem.

Also, we get a principle on the receiving end:

• Accept all feedback.
• Evaluate any feedback later, not on spot.

You can see how none of these principles is groundbreaking. They all make sense, and you might already know all of them. Unfortunately, they also take a lot of time and experience to be done well.