Plunge the blocked drain before attempting other unclogging methods. Place the mouth of the plunger over the drain opening.
Press the plunger down, and then pull it back up quickly. Repeat this multiple times to attempt to free the clog.
Remove the stopper from the bottom of the drain if you are trying to unclog a bathtub drain. Often, hair and soap scum will accumulate on the chain extending from the stopper.
Removing these obstructions from the chain can fix the clog.
Use a coat hanger on a bath tub drain after removing the stopper to attempt to pull loose any blockages which might have formed in the top of the drain.
Pour warm water down the tub drain, or into the bowl of the toilet. The warm water is more effective at breaking up plugs and can wear down the impediment.
Insert the end of an auger into the opening at the bottom of the toilet bowl or into the bath tub drain and begin feeding the auger through the pipes until you reach the clog.
Turn the crank of the auger slowly while apply pressure. This will cause the bit at the end of the auger to spin and to begin tearing through the clog.
Continue cranking slowly as you pull the auger out of the drain. This ensures that any persistant residue remaining on the walls of the pipes will not catch on the auger and prevent its removal.
Use a chemical unclogging agent on the drain if water is still failing to drain at an acceptable rate.
Call a professional plumber if you have exhausted other options and the problem persists.