How do I balance a ceiling fan?
Most new fans comes with a balance kit. It includes a heavy clip and a set of stick-on weights.  If you don't have the balance kit you can buy one at a big-box home improvement store.


First, run the fan at each speed to
see where it wobbles worst. 
Put the
clip on one of the blades near the
middle and run the fan at that speed.
Check if the wobble improves or
worsens.
Repeat the process with each blade,
and narrow it down to the blade that
gives the most improvement.
Now, try moving the weight towards
    the tip of the blade and down to the
    hub, testing each time you move to
    locate the sweet spot.
Finally, attach the weight at that
sweet
    spot.