Minimal Redundancy: The less a database repeats the data in it, the better. Redundancy can cause issues such as Deletion Anomalies
Prevents Modification Anomalies by Design: This means anomalous modifications are prevented by using keys, not by enforcing an excessive amount of contraints. Otherwise, Update Anomalies may occur.
Matching the used RDBMS: This provides faster query processing, but for this, redundancy can be necessary.