FASA came up with a couple of interim uniforms between the TWoK space mountie costumes and the TNG PJ's. One was based on the TWoK cadet jumpsuit and the other was all black with a sash of department colour across the chest, some thin department-colour piping up the sides and a neat arrangement of the rank pips in a row beneath the rank insignia.
It's a shame they couldn't afford to show as much variation on TNG, but when you realize that humans are some of the shortest-lived species in the galaxy, its a little more plausible that we'd have the same uniforms for 80 years and same ships for 150.