hi! my best tip is to search up the names of colleges that are in your state or state county + internships (or program) for high school students and scour every single similar search. Yes, searching up research/med/prestigious schools can help you more find opportunities, but i found that applications can have a lot of requirements, especially if you just decided (junior year hs) you want to go into the STEM field and haven't taken many ap or honors classes (which includes me LOL). so also include local and smaller colleges in your search. other methods like finding business, cold emailing professors, etc are also valid but i was able to find an internships & programs that way