A trick, if you use colored pencils: sketch in the checkerboard pattern really lightly with one color (I used a light brown for the bottom right shape) then do a second layer with different colors. The base layer shows through a little so all the colors work together nicely.

Thin pencil lines (I use a mechanical pencil so the lines stay sharp) colored slowwwly with Prismacolor pencils (which I sharpen a lot with a hand-held sharpener) on rough, textured watercolor paper.

My sketchbook. Colored pencils, including the black line.

My sketchbook. Colored pencils, including the black line.

Can’t beat nature for color combinations! Snapped these pics in my neighborhood. Top: pencil and watercolor; bottom: pencil and colored pencil (and only loosely using the checkerboard pattern).

Fountain pen on sketchbook paper. This is one long line.