69 Dart short

Hello gang,
Guess I was a lil premature when I said everything worked after getting on the road. A shop installed new dash and used the old stock wiring. It turns out I have no running lights and tail lights...and I'm not taking it back to those robbers to fix so I'm taking a run at it myself before I take to another pro. I found the 20A taillight fuse blown. Replaced and blew again. Headlights, break lights, back up lights all ok. I'm planing on checking all the wiring visually next and seeing if I can spot anything obvious. Other than that....and tips or tricks on diagnosis?? Thank you.