Remove and clean the sink stopper or drain cover
Clear visible debris from the drain opening
Pour boiling water down the drain
Use a plunger to dislodge the clog
Flush the drain with baking soda and vinegar
Clean the P-trap under the sink
Use a drain snake or auger to remove deeper blockages
Check the vent pipe for blockage
Inspect for buildup in the drain pipes
Call a plumber if the drain remains slow