Draw a rounded rectangle for the backpack body
Add a curved top flap or rounded top edge
Draw two shoulder straps extending from the top and sides
Add a front pocket with a smaller rounded rectangle
Draw a zipper line across the main compartment
Add zipper pulls on the main pocket and front pocket
Sketch side pockets on both sides if desired
Add seams and stitching lines for detail
Draw a handle at the top
Refine the outline and erase extra lines
Add shading and simple texture details