While this is not essential, it is always helpful to do this prior to your visit. Even to instill oil into both ears at least 1-2 days prior to your visit is useful. In order to do this, just use some cooking oil, such as olive oil, canola oil, sunflower oil, or rice bran oil. It's best not to use any oil with a fragrance (i.e. baby oil), as this can irritate sensitive skin in the ear canal.
In order to instill the oil, use a dropper (can be purchased at a chemist), or put a small amount of oil on a teaspoon. For best installation, lie on your side and install the oil and place a large ball of cotton wool (nor cotton buds) into the ear canal gently so as not to allow the oil to escape. Stay on your side for at least 2-3 minutes. It is not necessary to warm the oil.