AMGMG HNNG THIS IS SO AMAZING. I've seen a lot of mediocre RotG fanart, but you've seemed to capture the characters very well for your first time. I also think the colors you chose for each of them work very well for their personalities.
I'm continuously drawn to Sandman -- I think he looks spectacular. Both the effects of the sparkles and just the way you've drawn his face is great. The lighting and shading are equally as impressive (if not more)
Personally, I would have liked to see at least hints of Pitch Black, but I understand that this is just the Guardians. I totally love the pictures and the transitioning/panels are super fly. Great job!! ~
I think you did a superb job on Frost's face (I think that trips a lot of people up) and on his eyes. I also think the technique you used on each of them fits extremely well and looks wonderful.