Tax withholding is formula based, and as already stated there is a lot of info out there that you can use to figure out what to enter on the W-4 you provide to employers to insure you don't get stuck with a large underpayment at year end. This assumes, of course, that your income level is relatively stable.
Internal Revenue Service is a great source of info. As screwed up as government agencies often are, the IRS website is actually excellent (a good use of our tax dollars, for once).
For the typical W-2 wage earner (no rental properties, no small business, etc.), there are only a few deductions available. Mortgage interest, property taxes and state taxes are generally the only meaningful ones aside from the dependents/personal exemptions. For those with kids, you may also qualify for dependent care credits, or the child tax credit...although these phase out at a level that will put a lot of working people in the NYC metro area above the limit.