Darktiste Sketchbook

[Rotohail]

Hmm, I'm not sure I want to pitch into the battle of wills taking place with the construction/perspective thing but the advice given does fit inside the category of "Form/construction" which is marked with a red squared (so high priority) withing your choice of focus. So it would be a good idea to work on that. Gesture can be informative or not, depending if you are doing a character design just for visual detailing or concept or one for animation, storytelling.
If design is your top priority you should really then start with graphic design and push your designs and shapes in some direction, I'm kinda of a starter myself on the topic so I can't really comment but you know the usual combine curves with lines, sharp angles with softer angles, large forms with smaller ones, hierarchies, shape language.
From the last one, the Han Solo redesign, the main changes I see (bear in mind I'm not too much of a star wars junkie so I had to check it) is that your changed his shirt from long sleeves to short ones, but gave him gloves that reach up almost to the elbow and the greaves or metal shin plates. So what would you say were those changes done for? Like what was your thinking when changing those aspects of the original design?
For the second part it does have an Archer vibe so good job! I would like to say you could try making the eyes smaller to fit within Archer's proportions.