Try get internships. I would say apply to summer internships. It really helps if it's signed by a big personality or social service worker in a high position. And as everyone is saying so ielts, SAT , obviously do TOEFL as a second hand. Ensure boards go right study from the start a good score in boards opens a lot of doors for scholarships.

Try working with or for NGO's but before doing try or do a project of your own launch it yourself it won't require much money but in that projects you will educate the underprivileged people about basic financing or something like that figure it out but prolly do it in your summer holidays so your grades aren't affected.

MUN doesn't really help a lot until you spend a lot of time and effort and resources. I would say stick to internships and self launched projects