These are a couple of sketches I have done recently in my little pocket sketchbooks. I usually start with a 4H pencil to lay down the initial shapes and then add value with a Prisma Color ebony pencil.
When I was younger I used to draw so lightly you could barely see the lines. I think it was because I was always afraid of not being able to erase. Now I kind of embrace that. Despite the fact that I primarily work digitally nowadays and ctrl+z is always there for you, I try not to rely on it so much. Not only does having to work around mistakes give the piece more character and spontaneity, I also find that "happy accidents" can really be worth it.