Here is the whole trick: pick one instrument and play it every single day for 99 days. Not an hour. Ten minutes counts. The streak matters more than the session.
I started with piano because it is the most visual instrument there is. Every note is laid out in front of you, left to right, low to high. You learn where the notes live once, and that map transfers to everything else.
After piano comes drums, then guitar. Same deal each time: 99 days, every day, no zero days.