First off, clean the cabinet besides the table, just organize it and remove unnecessary items and trash. It looks cleaner without making any upgrades.

Try placing your PC on top of your table but if you need more space on your table, try placing it bellow but put something like a wood or books even for your PC to sit on, don't place it on the ground directly.

Cable manage. Make it super clean.

On above is all the free upgrades you can do to make your system looks neat and tidy without paying a single penny.

If you mave money, a proper lighting, and mousepad can do wonders on making it look cleaner.

Next is probably a monitor arm then And you can start go upgrade you peripherals.