I'll tell how I wire 'em.
[100uf +], I use a metal DC jack, the barrel, if in a metal enclosure is good contact, so I make the pin + and the Barrel -, for NPN Neg Gnd. at least.
Actually I put the black and red wires to the - and + poles of the electrolytic, then put that on the DC jack, if there's not a cap across the power supply +/- already on the board.
Just one example of wiring and types of jacks....
Someone tell us why that's not the optimal way...probably because some effects may not like grounds here 'and there, better to use an isolated jack?