Add an extra egg
Replace water with milk
Use buttermilk instead of water
Add sour cream or plain yogurt
Add mayonnaise
Use melted butter instead of oil
Increase the oil slightly
Add an extra tablespoon or two of oil
Do not overmix the batter
Do not overbake the cake
Check for doneness a few minutes early
Brush the cake layers with simple syrup
Cover the cake while it cools
Store the cake in an airtight container
Add pudding mix to the batter
Use cake flour if allowed by the recipe
Add a little applesauce
Add mashed banana
Add pumpkin puree
Use room-temperature ingredients
Measure ingredients accurately