Stephen Jackson is giving some solid advice to D'Angelo Russell following his weed bust earlier this week ... telling the NBA star to keep his head up and be SMARTER with his pot moving forward.
As we previously reported ... DLo was cited for marijuana possession Wednesday at La Guardia airport after TSA found a fake can of Arizona iced tea in his checked bag ... with green stashed away in a secret compartment.
Stack is now going to bat for Russell ... essentially saying it's NBD because ganja's practically legal everywhere now but laws are laws, and the young hooper can't be getting in trouble.