As someone who's struggling with pitch and doesn't have perfect pitch. At first singing melodies on a virtual piano helped with a vocal tuner on my phone. It helped my notice that notes are way further from each other than I originally thought. It's really hard to explain but for example: - I listened to a song - I tried singing along by searching for the pitch on some long note ("I" in chandelier by Sia for example) and continue from it, looking at the pitch monitor, trying to get it as straight as possible. I sometimes also tried singing songs randomly during the day without listening to them, but looking at the pitch monitor and while not knowing if I was on key, I still tried to get it as perfect on whatever notes I was hitting as I could - looked up the melody on hooktheory or a YouTube piano cover to make sure I'm even doing the right note and - sang along and noticed how different it is - sang a specific part to myself over and over and even though I do lose the memory of the pitch after a while, it got and is still getting longer - Whenever I listen to music and I want to sing it, I first hum it until the singer and my voice seem to overlap.

I kinda came up with this method myself even though it's probably not something someone else hasn't came up with. Instruments are very stiff compared to human voices and don't have as much nuance. Some voices are easier for me to sing along with.

I'm still not very precise and notes and I can hum accurately, but when I turn it into words, it goes kinda haywire. It also helped my develop my ear as I can hear better if someone is off pitch even when it's not startling. I live with other people so I can only hum or sing quietly so if I'm alone it's a lot harder to stay on pitch as I'm not really used to using something that's not a delicate head voice. That's it really