Morgana's Q is her core weapon, but use it judiciously rather than relying on it excessively, and effectively block ally CC with her E (Black Shield).
As support, consider utility items like Rylai's first, while mid focuses on damage and Zhonya's. Her high survivability makes her strong in lower tiers.
Focus on predicting enemy movements and dominating teamfights by utilizing her Q and the R-Zhonya combo, which opponents find frustrating.
Stats
Q
W
E
R