If you are baking dark cakes with chocolate or cocoa and need to butter and flour the tin do not use flour but use cocoa.
Egg whites whip best at room temperature. Add a few drops of lemon juice. First, make sure the bowl and beaters are free of grease and the whites are free of any yolk. Grease and yolk will inhibit aeration. When adding egg whites do not beat them in the other mixture but fold in with a spoon.