A few ios app recommendations I'd like to make are:
- Rassel (a free and absurdly accurate pocket shaker app) https://apps.apple.com/us/app/rassel-pocket-shaker/id1575364...
- Ableton Note (Best 6 dollars I ever spent. It's a really fun way to experiment with musical ideas on the go. You can even record vocals and add effects.) https://apps.apple.com/us/app/ableton-note/id1633243177
Then there's some exercises you can do with just paper and pens: https://www.youtube.com/watch?v=1eqLmkWOU6A
A really versatile, affordable and fairly compact percussion instrument you can start off with as well is the Bodhrán; you can make some really great beats with it, see e.g. the opening scene of the film The Magdalene Sisters, just bodhrán and singing: https://www.youtube.com/watch?v=WxXFs8EL35o. Here's another version of the same song where the artist plays it with just his hand: https://www.youtube.com/watch?v=-mjWhMn-VnU
I knew how to practice effectively from my years in band, but I didn't use them because I was too busy rejecting who I was in high school.
Now I'm learning piano and I've joined a choir, and I'm actually getting better at things instead of being a perpetually mediocre guitarist/singer.
I much prefer playing guitar to piano or a choir.
I had discovered that music was one of my few interests that I could actually trade for social credit.