Tighten all the holding screws that attach the blades to the blade holders. A wobble can occur because the fan blades are not tight and move around in their mountings.
Wipe off every fan blade with a damp rag. Dirt build-up can cause a fan to become unbalanced. Remove all dust and dirt, then turn the fan on to see if it still wobbles.
Measure from the tip of each fan blade up to the ceiling. Each blade should be exactly the same distance. Any blades that are under or over the measured amount can be slightly bent upwards or downwards at the metal holder. Turn on the fan. If it still wobbles, you will need a fan balancing kit.
Unpack your fan balancing kit and find the plastic clip-on weight and several metal stick-on weights. Find the middle of any fan blade by measuring the length of the fan blade and dividing by two. Attach the clip-on weight at this middle point and then turn the fan on. If the wobble increases, go to the next blade until the wobble decreases. You have just found the unbalanced blade.
Move the clip-on a few inches up or down the unbalanced fan blade until the wobble stops. At the point where the wobbles stops, attach one of the metal stick-on weights and remove the clip-on weight.