People should take care to make sure that their hands are clean prior to washing their face, if only because it would be the logical thing to do. Since people are going to be using their hands to wash their face, it would be sensible to make sure that the hands are as clean as possible, to avoid doing damage when the action is supposed to be preventing damage. Aside from the prerequisite water, rinsing the hands with soap can help clean off any visible dirt and acts as a preliminary measure for getting rid of bacteria that might be on there.
Hot water is not advisable for washing your face with. This is a common mistake, particularly because it is a simple matter to confuse hot water with warm water. In reality, warm water is best used because it opens up the pores, allowing the water to flow in and wash things out. Hot water can do this as well, but has the potential to cause damage to the skin, especially if the skin is sensitive. Some people also advocate the use of cold water to close the pores afterwards. The use of cold water for rinsing closes the pores and prevents dirt and other irritants from entering the skin again.
Applying skin cleanser is advisable in between the warm and cold treatments, giving it the chance to seep into the pores and do its job. Applying such topical treatments on closed pores reduces their potency, so rinsing the skin with warm water is advisable. Small amounts are also best, particularly if the skin is sensitive. Cleansers and other topical treatments are best used from the forehead down, unless the instructions specify otherwise. Sensitivity to the cleanser should also be noted, because not all of them follow the same potencies and strengths. In some cases, using smaller amounts helps, but for others, switching to another product completely is the better option.