It is very difficult for a beginner self-taught musician, because no one will explain how to play this or that example from the book or what key signs should be in this key.
Today you can find a large amount of educational literature, in which almost everything is painted. If you decide to play classical music, then you have to learn the theory. This is necessary in order to be well oriented in the keys, to be able to improvise and come up with music.
If you are completely ignorant of music theory, it is best to start learning with intervals. Only after studying this section can you begin to study the keys. There are 24 keys in total. Two of these keys have no key marks, and the rest are characterized by the presence of sharps or flats.
What are the signs in D minor
D minor can be called one of the easy keys, since it contains only 1 key character - B flat. It should also be remembered that all natural minor keys can acquire temporary signs. For example, in a harmonic minor key, the 7th scale step will rise. If you project this rule for the key of D minor, you get a C sharp note. There is also a melodic type of minor scale. It will sound like a major, but with minor changes. For a melodic minor, when moving up, 6 and 7 steps will rise, and down you will need to play or sing a natural minor (in writing, the signs of an increase or decrease in a note are canceled by a bekar).
The circle of fifths, or how to learn to improvise
Determination of the name of tonalities by signs at the key is taught in music schools. You can learn the keys and key signs in them yourself, using the image of the fifth circle. It depicts tonalities depending on the degree of relationship. For example, at the top of the circle there are keys without signs, then there are keys with 1, 2, 3, etc., with signs at the key. Sharp keys will be indicated on the right, and flat keys on the left. If you memorize the fifth circle, then you can easily choose the accompaniment to the melody, improvise, and also understand the key, in which there are a lot of characters with the key.
How to determine the tonality of a piece by key signs
When learning an unfamiliar work, you first need to determine the key in which it is written. To do this, you should pay attention to the signs at the key. It is also necessary to take into account the ending of the piece, since the same key signs can be present in two keys - major or parallel minor. Only by considering these two factors will you be able to accurately determine the key of the piece.
It should be noted that this rule sometimes does not work in the works of the authors of the Expressionist period in music.