A critique is an analysis (unemotional/detached) and need not be a criticism (judgmental). There is a distinct difference. A long time ago, my painting mentor shared some valuable advice on giving critiques.
1. Praise the good/outstanding features in the image or piece. (Praise encourages.)
2. Then, make suggestions on...let's say...a corner of the painting. "What do you think about doing such and such over here?" If possible, give several alternatives. Have a discussion on possibilities. Ask the artist for ideas on what he/she thinks could be done in that corner.
3. Stick with technical aspects instead of inserting your emotional, personal opinions and knee jerk reactions.
4. End with positives and more praise to close the circle of discussion in a positive way.
The Result: A Win/Win
Another thing to consider is how sensitive artists can be...their innermost feelings are being expressed in their work. When discussing anyone's work, growth and excellence are the goal...not humiliation. Have your discussions in private.
Occasionally, a unique situation occurs where you may be at a loss for words. Sometimes unexpected things appear in a work. For instance, once a friend created a pink silo...think about it...need I say more? There was no away around this one. Had to simply, and softly, confront the issue head on by asking, "What does that silo look like? Do you really want a pink "silo" in your painting?" If that is your intention, then by all means, let it stay. If not, it may be time for some rethinking."
As creators, we need to step back and unemotionally access our work. Scrutinize...be ruthless. Next, ask someone whose opinions you respect to critique. If the information you receive is helpful, use it. If not....file it away for later. Never compromise your vision, your means of expression, or your integrity.