Wash or Wet the Clothes:
You have to wet the clothes before proceeding to shrink them. Launder them in a washing machine in warm water. Some clothes are expensive and delicate and can only be dry cleaned. You cannot risk laundering them in the washing machine. Instead you can just wet them with a water spray.
The amount of shrinkage also depends on the fabric type. Cotton and wool shrink easily when heat is applied on them while polyester shrinks very little and takes several repetitions to get the desired size.
Half Dry it:
The next step depends on the type of your cloth. If it is a thick material, let it air dry a bit and most of the water drain out so that you do not have to make the extra effort of blow drying that excess moisture. You can also use a dryer to half dry the clothes.
Hang it Properly:
When the cloth is half dry, hang them on a hanger or washing line. If the clothes are thin, you can move directly to this step. Hanging on a hanger gives you maximum access to all parts of the fabric. You can also spread the cloth flat on a hard surface.
Turn on the Hair Dryer & Start Working:
Turn on the hairdryer on maximum heat. Use a nozzle attachment if available. Focus the hair dryer on the fabric with a minimum 6 inches distance. Move it all over the fabric many times, stopping only when you feel it has shrunk enough.
Do the Selected Parts Only if Required:
The best part about using a hairdryer to shrink clothes is you can use a localized approach. If you want just the sleeves or the collar to shrink, this is possible with a hairdryer.