Having a large balance due with the tax return can be very shocking for us. There are many factors that affect the withholdings. Marital status, children, other sources of income besides the wages can all play havoc with the withholding computation.
We have a great estimator tool here..
W4 Estimator
You enter your information and it will help you determine how you should fill out the W4.
Completing the estimator with all sources of your income should prevent that large balance due for next year.
One of the most common mistake I see is if you are single and work two or more jobs or are married and you both work there is a box in step 2 box C that should be selected. The estimator should catch this but it is good to double check if you need to check this box.