When scooping the batter into the cake pans, I use an ice cream scoop to make sure I get equal amounts of batter into each pan.
When putting the cake layers in the fridge to cool, I place them upside down (parchment paper side up) to help flatten the tops and avoid the need to cut off the tops to level them off.
When scooping the frosting between cake layers, I use the same ice cream scoop to make sure each layer has an even amount of frosting.