Andreas J. Köstenberger, Benjamin L. Merkle, and Rob Plummer offer five suggestions for studying and retaining your Greek here. Make sure to read the explanations in the post but here are the five suggestions.
1. Read the GNT in your daily devotions.
2. Include Greek study in your weekly ministerial preparations.
3. Take a “Greek retreat” once or twice a year in which you read longer sections of the GNT, a technical Greek resource, or a Greek grammar.
4. Consider what elements of accountability and self-discipline may be applied to incorporate study of the GNT into your life.
5. Teach Greek.