Replace water with milk or buttermilk
Add an extra egg or two egg yolks
Use melted butter instead of oil
Add sour cream or Greek yogurt
Mix in instant pudding mix
Add vanilla extract or almond extract
Add a pinch of salt
Use coffee instead of water for chocolate cake
Add mayonnaise for extra moisture
Fold in chocolate chips, nuts, or fruit
Brush layers with simple syrup after baking
Frost with homemade frosting
Bake in a different pan shape for better texture
Do not overmix the batter
Let the batter rest for a few minutes before baking