Use milk or buttermilk instead of water
Replace oil with melted butter
Add an extra egg or two egg yolks
Add sour cream or Greek yogurt
Add vanilla extract or vanilla bean paste
Add a pinch of salt
Add instant pudding mix to the batter
Use cake flour instead of all-purpose flour if possible
Mix only until just combined
Bake in prepared pans with parchment rounds
Do not overbake
Cool completely before frosting
Use a bakery-style frosting
Add simple syrup to the layers
Fill and frost generously
Chill the cake before serving
Finish with fresh fruit, sprinkles, or chocolate shavings