If your drain does get clogged, you'll have to remove either the pop-up
stopper or the strainer to get to the source. If you have a pop-up stopper, pop
it up and turn it counterclockwise to remove it and remove any hair or
materials. If the water drains, you've cleared your clog. You can replace the
stopper. If you have a strainer, you'll need to get a pair of pliers to insert
in the openings and twist counterclockwise. Pull up the strainer and remove any
materials. Once again, if the water drains, you can replace the strainer. Turn
it clockwise and be sure to get it tight.
If that doesn't work for you, you'll need to get a plunger. Place a bit of
petroleum jelly around the rim to help create a seal. For greater suction, fill
the tub until the water line covers the plunger and stuff a rag in the overflow
plate. You will need a screwdriver to remove any screws around the plate.
Plunge rapidly, then allow the water to drain. You may have to do this several
times.
Clogs can be messy and annoying to deal with, but with some small effort and
you can avoid them all together. Try these simple preventative measures with
your drains. It could end up saving you a lot of hassle and money in the long
run.