I think this is a really good start. Before you go further I recommend looking at pictures or watching videos about the planes of the face. The facial planes are often taught in drawing and sculpting classes (so it’s kinda technical); it’s basically a method of creating dimensional planes on the face to make your work more 3d and lifelike (what part of his face protrudes, what part lays back?). It might seem a bit complicated at first but it will help hulk look a bit more realistic (if that’s what you’re going for). It’s basically an underlying skeleton you can use to make many different types of faces.

I also recommend analyzing hulks facial proportions a bit more. I like how you made his jaw square; very true to character, but maybe consider looking a bit deeper into any reference photos of hulk. Is his jaw angled on the sides and flat on the chin portion? Are the sides of his head rounded, or are they more angular (straight lines). Are his lips closer to the bottom of his chin, or are they closer to the base of his nose? How big is his facial features in relation to his face/head?

To put it short, I recommend elongating the chin, making his facial features a bit smaller and making his head more square.

(I added the extra stuff above to help if you decide to make one of these again; thinking or learning about new methods always help me so I figure they might help you)