It's certainly possible to improve verbal, but it can take a while. If you want to take the time, let us know what your experience has been so far and what materials you have available. A few general tips:
1) Read every day. Read GMAT material, books, science magazines, everything. Push outside of your comfort zone--if you don't like history, make yourself read history articles! Make sure you are working to understand the material on a paragraph-by-paragraph basis.
2) Follow timed problems with untimed review of those problems. Focus on understanding why each right answer choice is right and why each wrong answer choice is wrong.
3) Know your grammar rules! Our Sentence Correction strategy guide is a great source. Then, of course, you need to practice applying those rules on Official Guide problems.
4) Always know what the question is asking. Reading Comprehension and Critical Reasoning questions are much easier if you have taken a moment to understand the question precisely. Then, if you interpret the material carefully, you will often have a good chance of predicting the right answer in advance. Don't rush into the answer choices!
Good luck!