Plunging a Clogged Sink: Its the UP stroke that counts! A sink plunger works best when you plug up the overflow to keep the pressure in the right place, push gently down on the plunger and then pull it up with energy. Forcing down may just lock the blockage in tighter. Pulling the block back toward the sink will undo it from the same direction it was created.
Although a skirted toilet plunger can do a lot of good, in many toilets the same thing applies as in the sink -- you have to block off the little holes around the rim as in the photo above. You can use putty, even vegetable bags, but don't loose anything down these holes, as it is very hard to get it back out. And remember, it is the upstroke that counts.
One interesting gadget for getting hair out of a drain is a mechanics flexible pickup - a long flexible shaft with a "claw" that pops out the end to grab the hair. Here is one from Home Depot.
How about those pressure gadgets?
You will find many gadgets in the stores designed to push blockages on down the drain; from cans of compressed air, to air plungers, to attachments to a garden hose. Don't ever use any of these! The drainage piping was never designed to withstand pressure and you could blow the drain pipe right apart at the joints inside the walls. Even if you don't blow open the pipes, these gadgets often force waste up into the vent stack, the path of least resistance -- and now your drain will not work correctly until you cut open the walls and replace those vent pipes. Pull blockages back, don't blow them forward.