Check with your post-secondary institution on what scholarships they have available for students.
Keep track of your accomplishments, volunteer hours, and work experience in high school (the easiest way to do this is to keep a resume!)
If you're lost with where to start, Google "Scholarships" and you can find TONS through that.
Keep track of scholarship you want to apply for, have applied for, and have received using this document from Mapping Your Future: https://docs.google.com/spreadsheets/d/1b5updQjxV7dwP5wGHlkK-7ytqdDXA8Bm/edit?usp=drive_link&ouid=116789011539758348917&rtpof=true&sd=true