How can I practice my voice as it changes?

I’m a guy and just turned 15 about a month ago and my voice is rapidly getting deeper. My dad has a pretty deep voice so I’m expecting mine will end up like his. My whole life I’ve loved singing while I play guitar and piano, and I’m not confident in much but I’ve always thought I have a pretty good voice. As my voice is changing, I can’t hit the notes I used to anymore and my falsetto is always crackly and strains my vocal chords. Also, when I sing deeper than I used to be able to, I am out of tune most of the time and it overall doesn’t sound that good. Do you have any tips to improve my singing as my voice gets deeper and overall being able to sing better? Thanks.