How many do you have? Generally, the more exemptions you claim on your W-4, the more money you get in your paycheck and the less you get at the end of the year. You might want to be careful as it is not an exact formula that will get your desired refund. My general advice is if you are entitled to three, don't put more than two. In this way you won't be too disappointed at tax time.
https://www.irs.gov/pub/irs-pdf/fw4.pdf