No matter which wax you decide to use (we will observe the options later in this article), the appropriate way to start is to put base coat on your board.
How it differs from others?
Base coat is typically a hard wax, that easily stick to a clean board and gets into the "bubble" shape. This layer you put once you prepare your board for use and leave.
How often to change it? How often do you need to relax your board?
It's all individual in time frames and depends only in your wax conditions.
There is a need for full relax of the board if you see that in some parts wax totally disappeared and does not stick anymore to the board. For daily basis you do not need to do anything with your base coat.
In addition to base some people use wax pads to put it on. Using it you may receive a beautiful wax picture which will differ from the regular square net that you create by wax.

This is the point where experiments start.
Top coat is wax that you put over the base and typically add before each ride to make sure you have enough for the session. Wax that is used for it is typically softer and more sticky.
This coat is the one to create tension between the board and your feet.
Which wax to choose for that?

To differentiate that role from that of "key" modeling when a modeling source moves behind the object, it is typically called a "rim" or "accent" light. In portrait lighting, it is also called a "hair" light because it is used to create the appearance of physical separation between the subject's head and background.

A typical studio lighting configuration will consist of a fill source to control shadow tone, a single frontal key light to create the highlight modeling clues on the front of the object facing the camera over the shadows the fill illuminates, one or more rim/accent lights to create separation between foreground and background, and one or more background lights to control the tone of the background and separation between it and the foreground.