Renting means the two easiest storage upgrades are off the table: you can't screw a rail into the cabinet door, and you can't swap the base cabinet for one with drawers. You also can't leave adhesive scars behind at move-out. Everything below adds real storage and comes out clean.
Start with the door, without a single screw
The inside of a cabinet door is the most wasted surface in a rented kitchen. A hanger that hooks over the top edge of the door needs no tools and no holes — the no-drill under sink cabinet door back hanger ($23) fits standard doors and gives you two shallow tiers for sponges, gloves, dish brushes, and a bag roll. When you move, it lifts off and comes with you.
Be careful with adhesive hooks
Peel-and-stick hooks look renter-friendly until the finish comes off with the tape, and under sink cabinets are humid enough that adhesive lets go on its own. If you use them, keep them to light items and test a hidden spot first. Anything holding weight should be hook-over or free-standing.
Choose free-standing over fitted
Skip anything that mounts to the cabinet wall. A free-standing tiered organizer does the same job and leaves nothing behind. The SinkFlex 2-Tier Pull-Out Organizer ($33 for two) adjusts to whatever cabinet the next lease hands you — expandable width, height-adjustable shelves for pipes, and pull-out baskets so the deep back of the cabinet stays usable.
Protect the cabinet floor
Cheap particleboard under a rented sink swells the moment a bottle seeps. Put down a wipeable liner or a shallow tray under sprays and detergents. It costs a few dollars and can save your deposit if a cap leaks while you're away.
Keep the plumbing reachable
Leave the shut-off valves and the trap clear. If a leak starts, you want to reach the valve without unloading the cabinet, and your landlord's plumber will need the same access. In an older rental this is not theoretical — the fittings under a rented sink are often the oldest hardware in the apartment, and you are the one who will notice the drip first.
Pack the cabinet like you'll move again
Keep the boxes or at least remember which pieces adjust. A unit that expands and adjusts in height moves to the next kitchen; a rack cut to fit one cabinet becomes trash on moving day. That's the whole reason renters should pay slightly more for adjustable over fitted.
Moving soon or just tired of the mess? Shop the No-Drill Door Hanger or read the under sink organization guide.