Can anyone tell me about the rules of improvisational accompaniment? I need it urgently. Can someone who knows please tell me? The more detailed the better.

Which key do you want to learn to play first? First, master the scales of that key. Then you will have succeeded in the first step.

Then first practice the positive triads in that key, and then practice the secondary triads. Once you are familiar with all three chords, you can try the seventh chord. For dominant harmony, you can even use the ninth and thirteenth chords.

Pay attention to the position of the bass with your left hand, and try to connect the chords with your right hand as smoothly as possible, so that the listening effect will be better.

Insert sounds into the gaps in the melody of the song so that the accompaniment can speak and form a dialogue with the melody of the song. The blank place can be one note, two notes, several notes, or a scale, etc.

After getting the score, you also need to analyze the paragraphs of the song. Generally, the songs are two-part or three-part, and the texture contrast between the paragraphs will pop up. For example: A is still, B is moving, A is still.

Impromptu accompaniment requires accumulation. When listening to music, you should pay more attention to feel it. If you think it sounds good, then explore why it sounds good and what makes it sound good. Analyze his chord usage, rhythm usage, and even the matching of instruments (i.e. orchestration). After you accumulate more, you will find that ordinary pop music only has a few things, and it is the same whether you play it or not. By then you will have improved.

The above are some of my experiences. If there are any mistakes, please criticize and correct me.