Face 30-second warm-up

I like the eyes, they have a lot of expression. Definitely very free moving and energy in the lines.

I can definitely see the face on this one, at least the red represent the lips I think, good job!
I think caricatures are all about the expression, sadly for this one I can't really get the feeling, perhaps it is a bit upset? Also I know you had only a few seconds to make it, so I want to congratulate you for what you have here :D

This looks fun! I think you would benefit from studying head construction and anatomy. Try drawing around 100 skulls in your sketchbook (look at reference and simplify the construction with basic shapes.) I highly recommend you take a look at Andrew Loomis's "Drawing the head and hands." and "Fun with a Pencil." Once you have that basic understanding of anatomy, it becomes easier to push and exaggerate features, simplify, and create funny caricatures that look clear with intentional and decisive strokes. I suggest trying going for fewer strokes and make each of them have a purpose (follow the form, create contrast, show features, express emotion, etc...) Also, take a look at other caricature artists. Your work reminds me of Al Hirschfeld, try making master studies from him. You will certainly learn a lot. I hope that helps a little bit, keep creating and making fun work!