This is a common problem. Often, we are able to answer verbal problems intuitively without any need for study. However, this approach breaks down at the higher difficulty levels. When the problems get hard, our everyday intuitions aren't enough--we need rules! You could certainly get some tutoring or take a class, but it may be enough to study on your own. I will of course recommend Manhattan's verbal strategy guides, but one way or another, you need to learn some reliable strategies that will support you when the questions get tougher. You also need to get in the habit of reviewing your work to determine why each choice is right or wrong. Sometimes the verbal section doesn't seem as logical as quant, but there are still clear rules, and this kind of careful review is the best way to learn to apply them consistently.