NEVER claim exempt ... instead simply increase the number of allowances on line 5.
The IRS has two qualifications for claiming "exempt" on your W-4, and you must meet both. You must have had a right to a refund of all federal income tax withheld during the previous year because you did not have any tax liability, and you must expect a refund of all federal income tax withheld this year because you don't expect to have any tax liability.