These three drawings were done with different pencils ranging in hardness from 2H to 9B. I don't have the patience to sharpen and shave the points and lay marks side by side, as is sometimes recommended, but the different pencils used together still give a nice effect. Using a range of pencils is better than using one pencil and varying the pressure for lighter or darker lines. One drawback with pencil is the shiny surface in the dark areas. The top drawing is done with woodless graphite pencils, which I think gives the best results for the way I draw, without the shine.
Of course, if one are doing a walk and draw outside, one cannot carry and use five or six pencils. I don't have enough hands and can't tell the pencils apart easily. Outside I use one pencil, but again have discovered that a soft woodless graphite pencil is a good choice, because I can get sharp lines, and use the side for broad lines.