Let's take a look under my kitchen sink, as it looked a couple weeks ago:
Yikes. Cluttered. I started by taking everything out, including the linoleum the previous owners had set in there 20+ years ago that was curling up. Then I sorted through stuff & decided what didn't need to go back in - like a full ice cream pail of plastic lids (our recycling service doesn't take them but the local school can recycle them) and a handful of chemical cleaners I no longer use. And yes, we do have child locks on these cabinets!
Ahh...clean. Except for the woodwork around the cupboard, which I'm now noticing really needs to be wiped down!
Then I cut a new mat for the bottom of the cupboard using some leftovers from a vinyl floor we recently put in our laundry room/main floor bath. Looks spiffy, right?
Then I replaced the items I deemed worthy of under-sink space, basically dishwasher detergent, a roll of paper towels (we don't use them often, so I just keep one roll under the sink), trash bags, an empty ice cream bucket for more lids, a plastic basket with extra dishwashing stuff, and our recyclable paper box. There's also a bottle of bleach & a kitchen fire extinguisher tucked behind everything on the left side...rarely/never used, but available if needed!
Much less scary! :-)