As you might guess from the title this is about 'Wobbles'. There are 2 forms.
A speed wobble is a wobble you get when riding, its usually when you are going up to the area where you are not used to going that quickly.
Most often this occurs with new riders, or even riders who have been riding years but get on a faster machine than they are used to.
The best way of solving this issue is to ride up to a speed where the wobble starts, then back off a little, then, build back up to the speed again, and repeat the process; through this practice you will eliminate the wobble.
Also an important part to the process is being relaxed (which is what practice does - it makes you more relaxed as you get acustomed to the feel of the wheel). Breathing deeply is a good way of smoothing out the wobble.
Now there is a wobble under heavy braking AKA a 'Braking Wobble'. This is usually because under these conditions your body is much more ridged. But it can also be foot positioning; if one foot is slightly more forward it can cause uneven pressure when harshly leaning backwards. NOTE: foot positioning rarely applies to a 'Speed Wobble'