Do you have dependents?
Just fill out the W-4 accurately. It has 4 pages, not just the front page, and the worksheets on the other pages will help you out. Be sure to include the social security, because it could be taxable at the federal level depending on your spouse's income. Or use the IRS calculator.
https://www.irs.gov/individuals/tax-withholding-estimator
Assuming you file jointly, your taxable income will put you in the 10-12% federal tax bracket. The W-4 system (the form, and the calculations used by employers) are designed to withhold the right amount of tax so you get a small refund and don't owe.
There may be a different PA-specific form that you can also give the employer if you don't want them to use federal assumptions for state taxes.
