Remove any visible debris from the drain opening
Pour boiling water down the drain
Add baking soda into the drain
Pour white vinegar into the drain
Let the mixture sit for 10 to 15 minutes
Flush the drain with hot water
Remove and clean the sink stopper if present
Scrub the drain opening with a small brush or old toothbrush
Use a drain snake to clear hair or buildup
Repeat the process if the drain is still slow
Clean the overflow opening if accessible
Wipe the sink dry after cleaning