Saw your depiction of Dakal! I'd say you got the pose and general body language right in a big way, especially when you compare to the more extroverted members of the crew. It seems fitting to have his attention half on a PADD! And I would definitely listen to whatever he had to say.
So overall, you've definitely conveyed the sense of the character and that's more than half the battle!
Bear that in mind should you choose to read my suggestions. And you are obviously NOT required. It is there should you choose to consult it, and kindly hidden should you choose not to.
Now...this may be WAY more Cardassian information than you want, so you click the spoiler button at your own peril.
(I have NOT incorporated any specialized terminology or set in stone any suppositions I have made in my own fanfic, so this is safe!)
I would suggest, perhaps, adjusting some of the colors. The skin could perhaps stay that color, IF you accept the makeup seen in "The Wounded" as canon.
But the hair should probably get darker...Cardassians seem only to show grey once they've reached a more advanced age (ex. Tekeny Ghemor or Mila), and Dakal was a young character. Brown to black would make sense--though if you accept "The Wounded"-style Cardassian makeup as legit, I would tend towards brown. Otherwise, if you do increase the grey on his skin, I'd darken his hair to more of a black-brown.
His irises are a bit hard to see, so you might want to give them a color that keeps them from getting swallowed up by the whites of the eye.
The last comment I would give you pertains to the ridging structure of the neck. If you look at reference pics of Cardassians, you'll notice that the larger scales are only seen down the sides of their necks, not by the sides of the larynx as you've also shown them.
Anyway, I apologize if that was too much information...I have been accused by quite a number of people here of BEING Cardassian.
Overall, for a first sketch, that's great.
AND...I must add my compliments for the Pazlar and Modan drawings! I particularly like them as well.