Hair is the main source of clogs in shower and lavatory drains. Over time, hair and soap scum team up to form a clog that can slow your tub or sink. To prevent clogs from forming, you must stay vigilant in keeping hair from going down the drain.
Use tweezers to remove hair visible in the drain. You may need to use your fingers to get the hair out too. It's best to wear latex gloves because drains can be very dirty and slimy. Use your finger to remove the slime and soap scum from inside the drain. If you need to, use an old toothbrush to scrub away stubborn slime. Clean the drain with an abrasive cleaner and a rag or sponge and then run hot water for a couple of minutes.
When you're done cleaning the tub drain, invest in a drain screen or strainer that collects hair and keeps it from going down the drain. You'll have to clean hair out of it regularly, but it's better than dealing with a bad clog down the road.