What competitions should I enter to boost my high school profile

I don't know what major you're planning to do but try to do well in competitions related to your major. There are actually quite a few competitions you can do in a variety of areas, so research them and find which suits you. However, if you are planning to be a STEM major, participate in the Regeneron Science Talent Search. Its winners include Nobel Prize winners, National Medal winners and etc. If you are an artist or a writer, aim for winning the Scholastic Art and Writing Prizes. Its winners include people like Andy Warhol and Stephen King, and it tends to be (from what I have seen) one of the best predictors of which rising creators will be influential.