Draw a simple rectangle for the seat
Add four straight lines downward for the legs
Connect the back two legs upward to form the chair back
Draw a rectangle or curved shape for the backrest
Add horizontal or vertical support bars between the legs if desired
Adjust the proportions so the backrest is taller than the seat
Refine the lines to make the chair shape clear
Erase extra guide lines
Add thickness to the legs, seat, and backrest
Shade lightly to show depth and form