I’m sorry I’m not really good at giving advice but I’ll try. Something the you should NOT do, is just straight up saying “I like you”. You should rather slowly inch towards the topic in a casual conversation. You should then list all the reasons why you like them. Also if you can see their face I recommend doing the tingle trick (looking at the left eye, quick glance at the lips, then to right eye)
I hope that this at least helped a little bit
Good luck 👍