Hey @Valerio Pilotti, great job on these studies. I can tell you've really been studying the fundamentals, these are really solid in terms of placement and perspective. There really wouldn't be much I'd change. If your goal is to make drawings with more likeness and style, then I'd say your fundamentals are fine but your decisions feel like you're copying what you see versus what you want to see. For example, on the male drawings I can see his head is more triangle shaped, as in with a bigger jaw and a smaller cranium. Yours feel like you're drawing a Loomis head applied to his versus using it as a tool to push his outstanding features. What I'd say is watch @Court Jones's video Finding and Using a Spirit Animal to Draw the Face. Even if you're not interested in caricature as a career, it's incredibly useful for thinking of how to push shapes to find a likeness/ style in portraits. When I was at the Watts Atelier, @Jeffrey Watts used to say that even the great artists like Sargent or Rockwell would caricature their portraits. Less extreme than a pro caricature artist obviously, but they would take bits and pieces of their subject to push and as a result would get a stronger license. Again, great job and keep up the good work!