One thing that might be confusing in the beginning when learning lighting is how the Strength value effects different light sources. For example, when you add a new spot lamp, the default Strength is 1.0. However, this is so weak of a Strength that when rendered, it will produce almost no noticeable result, which might make you think the light is "not working":
In order to get a noticeable result in your render, you might need to set the Strength to a value in the hundreds, or perhaps even in the thousands (if your light source is very far away from the desired target):
However, the Size of the lamp can also greatly effect how it lights your scene. Notice the difference between a Spot lamp different sizes:
Size of 0.100 & Strength of 1000
Size of 10.0 & Strength of 1000
Increasing the size makes it darker because it simulates increasing the area the light is coming from i.e. Same power over larger area spreads light thinner.
Also, if you are using a plane with an Emission Shader, depending on the size of the plane, you might need to use different strength settings:
Here, notice how if the emission plane is much smaller, a strength of 300 produces much less light in the scene:
So, experiment with the size and strength settings of your lights to achieve the desired result.
Visibility of Lamps vs. Emission Shader Objects
One of the biggest differences between lighting you scene with a lamp and a mesh with an Emission Shader is that a lamp will provide light in you scene, but the light source itself (the lamp) will NOT be visible in your render. For example, in the scene below, you can see the spotlight lamp in the 3D Viewport, but on the right, when the scene is rendered, you can see the lamp's light in the scene, but the lamp itself is not visible at all:
However, if if you use an object (such as a plane) with an Emission Shader added to it as your light source, both the light emitted by the object AND the object will be visible in your render:
Professional or Not?
There really is no one correct answer for "what is the most professional way of lighting". If you are actually using Blender professionally to produce a finished product for an employer or a client, then the best way to light a scene is the way that pleases them. If you are trying to produce something for yourself only, then the best lighting arrangement is the one you find most pleasing.
For example, if the goal is to create an anime-style scene with Blender, then you will need a lighting arrangement that achieves this goal:
If you want to create a more realistic looking, yet still somewhat cartoon-looking image, you will need a different lighting style:
If you want to create a photo-realistic result, you will need a photo-realistic lighting arrangement:
Study and practice will help you learn which style of lighting is best for achieving your goals. In this regard, searching Google for tutorials on lighting can help you find information on lighting in all different kinds of formats -- books, websites, videos, etc.
However, since Blender changes so rapidly from version to version, books tend to get outdated quickly. Therefore, YouTube video tutorials are one very good source of up-to-date information. If you search YouTube for "Blender tutorials lighting", you will find many useful tutorials. In fact, you can search for "Blender tutorials" and find excellent information on all aspects of Blender and you can learn quite a lot from them.