Check the reel for overall function. It should crank smoothly without binding or grinding, and the bail should close cleanly with a sharp snap. Test the line roller by sliding a toothpick against it. If the roller binds, disassemble it, and clean and oil the bearing or bushing underneath it. Lightly oil the pivot points on each end of the bail. If the bail still binds, it's probably bent. Try to correct this by gently hand-bending. Next oil the handle, the anti-reverse switch, the bushing or bearing where the crank joins the body, and under the screw cap on the opposite side of the crank axle.
Remove the spool and disassemble the front drag. Wipe out the inside of the spool. Now check the manufacturer's specs. Most drag systems with synthetic washers (like Teflon) are designed to run dry. Others (typically those with feltlike washers) take just a whisper of waterproof grease stroked into the fabric. Leather drag washers should be lubed with neat's foot oil. Once reassembled, the drag should turn smoothly at both light and heavy settings. If not, get new washers from the manufacturer.
Lightly spray the entire reel (but not the line) with WD 40 and wipe it dry with a soft cloth. Make sure to leave the drag backed all the way off so the washers aren't compressed during storage. And if the line on the spool is last year's, replace it. Even premium line isn't very expensive, and if you're chintzy now, you'll be sorry later when the old stuff breaks.