Some measuring cups are made for measuring dry ingredients, and some are made for liquids. Maybe you already knew this, but if you didn’t, it’s time to stop using your liquid measuring cup to estimate flour amounts. You can’t use one for the other without sacrificing accuracy.
The most accurate way to measure dry ingredients is to weigh them on a scale. If you don’t have a scale, spoon the ingredient into your dry measuring cup (as opposed to dipping the cup into the ingredient) before leveling it with a straight edge, like a table knife. You’ll get a more consistent result this way.