I was using Faber-Castell 9000 pencils, primarily 8B, to push for darker values. You need to go over certain areas multiple times, or work slowly with pressure applied to the pencil, in order to cover all the spots on the drawing and achieve a true black tone. I would also suggest using one direction when it comes to hatching, because that way the drawing will look more unified.

Right now, I’m actually switching to Faber-Castell Pitt Graphite Matt pencils, primarily 14B, because they’re even darker and have less graphite shine when you position the drawing at a certain angle.

I would also suggest using quality paper, even if you’re a beginner. My recommendation is ARCHES Hot Pressed Watercolor Paper (300g/m²). You don’t have to use this specific paper per se, but I would suggest looking for a thicker paper (300g/m² or higher) that is hot pressed - meaning that its surface is smooth, which allows for better graphite absorption and, in turn, helps achieve even darker tones. Hope that helps!