Among the proven techniques for improving test scores is regular exposure to skills that will be required for those tests. Daily exposure to language skills -- including skills of spelling, capitalization, punctuation, and grammar -- will build students' skills and increase test scores.
After my students write a piece I have them leave it on their desks when they go to lunch or special area classes. I place a Skittle on each correct punctuation mark (and I usually put one or two one if they indent a paragraph). Let me tell you, Skittles are the great motivator!