Something I learned about a moth after I started backing away from the box and baking from scratch...sift your ingredients. It gives the cake a much lighter feel.
How I do it? I put all my dry ingredients (flour, baking soda, baking powder,etc) into a bowl. I dump cupfuls into the sieve or strainer. Then I sift it directly into the beaten butter. It gets all of those clumps of flour and sugar and blends the ingredients together really well. Happy baking!!!