Softer lines are also better for creating little wrinkles without having them stand out too much. I'd recommend you'd use a softer pencil like a 2B
You'd actually use an H pencil to get lighter lines. (H pencils)Harder = lighter / (B pencils)softer = darker when it comes to pencils.
The drawings are pretty good, it looks like you are drawing symbols of what you are seeing rather than drawing what you are actually seeing though. I don't know if you're drawing from life or memory though. If you're drawing from life try and capture what you're actually seeing rather than simplifying it into something you think resembles what you're seeing. I don't know it's hard to give advice when it comes to drawing, for all I know this could be a look that you're intentionally going for. Anyways, the best thing you can do is to just keep drawing man, keep it up.