Join an amateur musical theatre group. That’s how I learned to sing (granted I was much younger than you).

have lots of time

That’s all you need. Pick an instrument and buy a cheap example, and use YouTube tutorials as your coach. My parents have gone from zero piano knowledge to banging out a few classics in about a year even though they barely have any time to practice at all.

If you’re looking for something more structured, classes and lessons are good too. I used to take guitar lessons and though I don’t anymore, I played a lot better back then because I was constantly being pushed to practice and learn new stuff. Don’t feel like you have to stick with the first instructor you find though, sometimes you’ll start lessons and just not “click” with the person teaching you, if that happens let the month (or however many you paid for) run out and try again with someone else.

The hardest thing is going to be forcing yourself to practice instead of, idk, browsing the internet or however else you’re currently spending your time. You’ve gotta find a way to get into the mindset that grinding out practice is fun, or at least more interesting than the alternative, otherwise you’ll do what I’m currently doing and end up with a bunch of nice musical kit in your room that you never use.

Come to think of it, I used to really like playing Rocksmith, so if you’re interested in the guitar that’s my app recommendation. Ubisoft is currently pushing Rocksmith+, which is a subscription service that replaced the main game - but you can still buy (or 🏴‍☠️) Rocksmith 2014 and mod in community-made songs. If you go down this route this is the website where you can get them.

Have a musically inclined friend give you a quick lesson and let you try out an instrument. If you like it, you can save up some dough for private lessons, or go into a music store and find some introductory books. For most instruments it’s necessary to learn how to read sheet music, with the exception of imo guitar which you can get by without. I think everyone should at least learn some basic music theory like all the notes on the staff, flats and sharps, and how to count time and rhythm and stuff.

Learn how to play some parts of your favorite songs, maybe play in an ensemble if you learn enough and stay interested. Play with friends/jam. Play with people who are much better than you and learn from them.

If you develop both your musical talent and your taste for music, it’s kind of like developing a new sense or learning a new language. In this one jazz guitar book by this guy Mickey Baker he says something like “you begin to develop a soul for music” by listening to, playing, and appreciating music. I think that’s a good way to put it.

I have played guitar for 16 years, took lessons for 6, now I just noodle around when I should be working. It’s very fun. It does take some dedication though, but the results are well worth it.

Everyone is posting good stuff but my main advice is to have very small goals. People learn music like they do language, once you’re an adult it’s much harder especially if you’re learning by yourself. People get confused that music learning is a talent thing, it’s not, it’s not anymore talent than a person learning Mandarin as child or as an adult. It all depends on how much you get to use the skill and how diligent you are. That being said get a teacher if you can.

If you can’t or are not that serious- in fact even if you do:

1. I would pick up piano if I were you. It’s very visual and it teaches a very encompassing approach to music.

2. I would try to find Youtube videos on “intervals.” Really try to learn what intervals are, spend a lot of time with it. Learn to sing every interval. Ask questions, hell- ask me questions. All harmony and melody is made of intervals, therefore, if you know your intervals very well you should be able to figure out harmony and melody. Picking up the piano will assist you in learning intervals.

3. I would also get an app like Tunable and sing a single note into it with the goal to keep the note perfectly in tune for as long as you can hold your breath. Being able to hear if something is in tune helps with hearing intervals better. Like do this one simple thing daily, I feel like music learning is a lot of getting really good at simple small building blocks.

One thing that helped me understand music better was singing/humming along to music out loud. in the car or at home or whatever. Just more practice. Even if it’s not good.