This is an awesome guide! I mean, this will help me a lot for my future comments, I usually just submit short comments saying "Oh my god, amazing job on this! I really like the concept and everything on this one! Awesome work here!", or add "I like your new shading style you have here!" if the artist has drawn it with a new style, or add "I really like your style, it's definitely unique!", if it's an artist I just discovered.
I usually just comment like that, since most artists I watch have the same style and kind of concept for every new picture they post, and it's difficult to comment something new, because of that. And sometimes when I can't think of anything new to comment, or if I feel that the artist probably won't reply to my comment because they haven't replied to all their other comments so I shouldn't bother wasting my time to comment something long that the artist probably won't even look at, I just favourite and run away. But I assume that it'll be totally okay with them, because they get an average of at least 150 comments that they won't even look at or reply to, and that they're okay with faving and running and they won't get butthurt for not commenting. On the other hand, I get disappointed when I work really hard on something and only get 3 comments, I mean, I once had a picture with 65 favourites but only 2 comments. I've only critiqued twice, on the same artist's art, but this will definitely help me write more.
Incredibly worthwhile guidelines. I've noticed in my brief time here that most users do the "Favorite Fly-by" and I'll admit, there are times I do the same. For me, I have trouble formulating constructive comments that I think will be worth reading; I hate to bother artists with a simple "Great job!" on every other work of theirs. I feel that's just another fly-by. On pieces that really speak to me, or make me feel something, I do comment, though it still takes me several minutes to ponder what to say and how to say it. Granted, I am socially awkward in every sense of the word.
But lately I've been feeling bummed about having received few comments since uploading stuff. I know I'm not good, but that's also where having honest critiques would help out. So I'm taking the comment pledge - to start leaving comments while I browse galleries and every time I favorite something. Hopefully I can help out and support other artists who might feel the same as myself.
And I will be referencing your formula often. Thank you!