Draw a long, winding line across the page
Add a second line parallel to the first to form the river banks
Vary the width to make the river look natural
Sketch curves and bends along the river path
Draw smaller branches if you want tributaries
Add rocks or pebbles near the edges
Draw ripples or wave lines on the water surface
Add reflections of trees, mountains, or sky
Shade the river darker in deeper areas
Leave lighter areas for highlights
Add plants, grass, or trees along the banks
Refine the outlines and erase extra sketch lines