The best way to plunge a toilet is to slowing push the plunger down until it makes a good seal over the hole at the bottom of the toilet, then pull the plunger handle quickly towards yourself. This will pull the clog back towards you, allowing the clog to loosen. Once the clog is loose enough it will free the clog and the toilet will flow cleanly.
Most clogs are caused by flushing items that shouldn't be flushed. Paper towels are once of the worst offenders. They are specially designed not to break apart in water like toilet paper, so they tend to wad up into a ball clogging the toilet.
Just remember, PULL not PUSH.
