These are some texture studies and perspective practice I've done in my sketchbook using pencil as a medium. The last 4 images are practices of shapes in different perspectives done in ball point pen.
Texture study for wood
Zoomed in view of wood study
Texture study for metal
Texture study for glass
Study on animals and insects
Zoomed in view of the bird
3-point perspective practice
Zoomed in view of building
Cuboids in two-point perspective
Cylinders in one-point perspective
Practice on intersecting shapes
Practice on organic shapes