Tyger sketches

[Samszym]

Nice study! Definitely looks solid to me. That's not a quality I think about too much, I guess I'm more used to thinking about creating depth. I'd be inclined to say getting the drawing and construction correct will give you more solidity than nailing the values would, though they're both important of course.
Try to put any overlapping elements that you can into your drawings, it's a great way to add some depth. In your latest study the reference's nose breaks the silhouette of the head, so it's easier to tell it comes forward. I think that might have helped the solidity of your study a bit

Good luck, keep rockin'!