I'd recommend following the aspects of the system that interest you, if that's magic, the Street Grim, and Forbidden Arcane, if it's the matrix then Data Trails, Chrome Flesh for Cyberware and Rigger 5 for vehicles, If none of that interests you then perhaps the plot books. SR plot books are great, I really liked Book of the Lost and London Falling personally.
Well best of Luck and Have Fun!