How should I sing?

First of all, if you don't have enough breath, you can take a few deep breaths when you get up every morning, about 10 minutes. In fact, if you want to kill two birds with one stone, I suggest you also go swimming to make your body have enough breath. Usually there is not much time. If you are a student, you can hum songs while walking or ride a bike, which also helps to adjust your breath. Boy, cute or bass, I suggest you listen to more songs in Japanese anime. There are many lovely songs in it, and there should be songs suitable for you. Find the specific song title yourself.

As for breath, there is a poem "Thousand Sakura" that more practice will also help to adjust breath. But the problem lies in the lyrics, because they are in Japanese (there is an adapted version)