I guess i never tried and/or never knew how to

tbh its tricky since it really depends on

1. level of familiarity ( how close are y'all)
2. they're preference
3. availability
4. personality

ok this is just for me ok... so if i really like them id ask for their love language. you can search it and take a test. depending on what they receive then you can work with that.
ex: if they like "acts of service" do something nice for them like help them do errands and stuff.

anyway good luck!

I'm not an expert in this, but I think...
First, being friendly to them, showing them that you're conscious of them... The way you smile and look at them is important to show you may be attracted to them. Being present if they need something. Always dressed well when you get to see them...

I guess it depends on the situation. The person you like is a friend? Someone close to you? Or more like someone you ocasionally hang out, but they are not really a friend? If they are a close friend it can be very hard to show interest in a romantic way, because you guys are already close, so the person can interpret your attempts to get closer as friend thing. In that case I think is better just talk with them about your feelings and if they don't see you in that way, move on.
If they are not a close friend, but you guys are not exactly strangers, you can try to show interest in the occasions you are together. For example, you are hanging out with them plus a bunch of people, try to start a conversation with the person you like and actually listen to them, show you care about what they are saying. You can always compliment them as well, but not in a creepy way, like say something nice about their clothes or style first, or maybe even their hair, but do not compliment their body unless you guys are already in a very flirty situation. And also do not compliment them unless you guys already talked, it can be pretty creepy to receive a compliment of a complete stranger out of nowhere. I think things will occur more organically once you guys start to chat, you may discover things you guys have in common and those things may turn into future topics to start new conversations or maybe even into invitations to hang out just the two of you. I guess you should try to look your best as well? You don't need to wear a suit or anything, and I know most of us aren't exactly super models, but everyone has a nice shirt or a cute sweater, so yeah, it might be a good idea to wear what makes you feel cute or handsome (๑•ㅂ•)و✧

Such a good adviser (づ￣ ³￣)づ

More skinship (touching their shoulder and such, be sure to get consent), turn your legs to them while talking to them, smile when you make eyecontact (not while talking about serious things though) compliment them and talk about subjects they like, maybe share your food with them or buy them little presents (as long as they like it).

Thank u ~~ (づ￣ ³￣)づ

Oh okay, firstly, thanks a lot, you're a very kind human. Then, i'll follow your second advice because we're not close friends yet (we met pretty recently) .
Ah also you made me happy because that is exactly what i was doing ( well the beggining for sure) . I guess I was feeling a bit uncomfrotable because i'd never done it before (i used to never let anyone know whom i liked or deny it until it went away, don't ask why, even i have no idea). So yes thank you very much, i'll try my best, but then i'm starting to worry that i might be percieved as clingy or too flirty you know? I think the hardest part here is trying to not cross the line between a subtle hey i like you and being a weirdo. So yeah, i'll definetly try that thannnnks ヾ(☆▽☆)

Thank you for your replies! I guess I'll try to be cute and caring as you suggested, and perhaps PERHAPS they'll notice. (and for the touching part i'm not so sure because of the virus and everything but mostly because i'd lose my mind if someone did that to me ( in both a good and bad way, actually depends on whom))
And hum i'll hope for the best.
PS: Being cute is gonna be pretty hard, around them i feel like i can't really control my face/i'm being wayyy too expressive of this overflow of emotions, so first thing first, not looking like a psycopath, then trying to show just enough for them to tilt
Thanks again, good morning/day/evenin/night to you (▰˘◡˘▰)