Double up on your rods to increase your hanging space. If ceiling height permits, you can add a 3rd rod that pulls down for seasonal garments.
Use adjustable shelves so you can modify your system when required to avoid wasted vertical space.
Fixed shelves can be put on sliders to improve access to deep storage systems.
Use your floor space properly. Add shelves or cubbies to utilize this space for shoes or baskets.
Hooks and racks can be mounted on the wall space or back of the door to make sure no available space is wasted.
Keep smaller items in bins, baskets, or closed containers to keep them organized.
Add integrated lighting to help you find what you are looking for quickly. If no outlet is available in the closet, use battery operated puck lighting.