I feel that a common mistake when it comes measuring flour is to dip the measuring cup into the flour and scooping out the flour. I probably have been caught red handed doing this in my early days of baking. But this is a huge 'no no'.-->
Reasons being you can scoop too much flour, making your baked items very dry. Or you scoop too little flour, making your baked items wet and gooey.
To have consistently perfect baked items you should correctly measure flour by using a spoon to lightly scoop flour out of its container into a measuring cup and level the flour off with the back of a butter knife.