Research and Inspect
Do a little research to determine your piece's value before you restore it. Inspect it for marks or labels that may indicate its origin. If you suspect it's worth some money, consult a professional before proceeding with any work. Take photos of any markings or tags for your records. Removing a collectible antique's finish could lessen or void its value, so hold off on stripping or sanding until you know exactly what you have.
If you're not an expert furniture restorer, don't worry. It's easy to look for a few telltale signs of age. Feel underneath for dull interior corners. Partially unscrew a screw and look at the threads. If they have inconsistent widths between them, then the piece is probably pretty old. Remove a drawer and see if it has dovetail joints. If you find any of these things, the furniture is likely old and well made, and you should have a professional antique appraiser value the piece.