Generally, whenever one talks about lighting a bathroom, a wall mounted fixture above the mirror props up immediately in one's mind. Even though, this is the most common type of lighting fixture known to people since last century, there are wide varieties and styles of lighting fixtures that are now available in the markets all over the world.
There is no rule such that the bathroom lighting should be provided only in the ceiling or is better if it is provided at the sides or on top of the mirror. One has to fix the bathroom lightings according to one's taste and the mood that he or she wants to bring into the room. Even for a small bathroom, people, these days, go for two or more lighting fixtures. Thus, lighting is the most important factor to be considered in any modern bathrooms.
But the second aspect to consider when choosing your bathroom lights is safety. Clearly a bathroom is a wet area, and electricity and water are not the best of companions. Today however there's a very easy system in use which helps you to quickly and easily identify the type of light that's suitable for each area of your bathroom.
If you want to look your best then you'll probably spend a fair bit of time in the bathroom, but unless you have decent bathroom lighting you may not be seeing yourself in the best light.