Draw a simple horizon line
Sketch a few large triangle shapes for the mountain peaks
Vary the height and width of each mountain
Add smaller mountains behind or beside the main ones
Draw a second line to give each mountain thickness
Add a few curved or jagged lines for rocky edges
Shade one side of each mountain lightly
Leave one side lighter to show light direction
Add snow caps near the top if desired
Draw simple lines at the base for ground or hills
Erase extra sketch lines
Darken the final outlines
Add trees, clouds, or a sun if desired