There are lots of issues involved in any verbal score - the ability to read and comprehend, the knowledge of question types and the ability to pick apart the answers to match the words in correct answers to the passages.

In SC I recommend that you focus on the six big errors tested on this exam - know how to recognize them both in the sentence and in the changes in the answer choices. Also know what other parts of the sentence will guide the answer (i.e. the subject determines whether the verb is singular or plural). Get used to breaking each question into 2-3 different rules and know how to make the decisions for each of them.

In CR learn the different question types, what to read for, what a correct answer will contain and how close to the subjects in the texts do the answers have to be.

In RC I would learn to paraphrase each paragraph before reading a question, then go back to the passage and use trigger words to identify your own answer to the question without looking at the answers and finally eliminating answers that are not similar to your own - then going back to the text for more clarification.

HOpe that helps.