Power your fuzz / high gain circuits with noise problems from this.  Like most things, it’s not a silver bullet for your problems, but it will probably help.

Here’s a better technical explanation than I will ever manage.  There’s a few variations of this circuit – google is your friend if you want to find out more.

TLDR:  It will reduce ripple on DC power supplies a lot.

DC POWER FILTER / CAPACITANCE MULTIPLIER – POINT TO POINT AND VERO LAYOUT