I know Im one of the people on here who replies on every post they can and I hope I've given good advice, but I gotta tell you a secret...
Its been far more effective for my own artistic growth than it has been for just yours.
Everytime I see a post on here, I see the same mistakes I make all the time, and by trying to help other people after I look at their art objectively and by trying to give easy, actionable advice, I am also teaching myself, developing an eye and giving myself advice. All the tips and tricks are also stuff I've learned from just being on the internet for so long, but never had the energy to implement, because my eye for my own work is harsh and unfair and it makes it difficult to share, and even look at after Im done. Its still something I deal with.
My lines used to be so dang sketchy, guys. But helping people on here made me adjust, learn new approachs and now the first time I draw a line feels more and more correct. I feel like I've had an artist breakthrough, like I finally crossed a threshold. I would not have arrived at this point without giving critiques.
So if you come to this website, I highly reccomend looking at someone's work and critiquing it. This is one of the few safe spaces I know where its okay to do this.
Impostor syndrome and lack of experience really slows people down, I know it stopped me. But its fun to analyze art and Im always surprised to find out I know more than I think I do about fixing or adjusting stuff, and just haven't really thought about implenting the techniques until I point them out for someone else.
If you really are nervous about what to say, I reccomend looking for what looks right and what looks wrong and commenting on that. I once heard that your most valuable asset for developing artwork is your ability to tell when something doesn't look right. Critiquing is what you do to develope that feeling into something you can act on.