What type of paint should I use to decorate a kitchen appliance?
There are special paints for plastic. If there is nothing in the colour you want, you may use plastic paint as primer/undercoat and use acrylic paint on top of that.
Be aware that plastic has a very smooth surface, so you have to sand it first in order to give the paint some texture to hold.
You may also want to apply a layer of lacquer as a finish, for extra durability.