Participating in a pre-college summer program is an excellent way to begin your college research experience! These are an investment, but they will give you an advantage in the long run. They usually last 1-6 weeks and include training in musical theatre, dance, acting, Shakespeare, scene work, and anything else you might need for the audition process. You can also get a sense of living on campus and working with faculty with whom you could potentially spend four years!
There are various types of summer programs available, and the majority of them are somewhat tailored to individual schools. The University of Michigan, for example, has Mpulse, Carnegie Mellon has Pre-College Drama, and so on and so forth. There are also programs where you can collaborate with a variety of schools and their faculty. This is the type of program I attended. These are the ones where you can take a lot of classes in a short period of time, and if you're really committed to the college audition process in general, this is a good fit for you. However, if you're set on attending a specific school and want to increase your chances of acceptance, attend school-specific programs. Some people manage their time extremely well and can fit both into one summer, but I don't recommend it.
So I would advise you to do your own research! Once you find schools that you like, see if they have summer programs!
SCHOOL-SPECIFIC PROGRAMS TO START WITH:
Boston University Summer Theatre Institute (BUSTI): https://www.bu.edu/cfa/busti/
USC Summer Precollege Program, Acting Intensive: https://precollege.usc.edu/summer-programs/acting-intensive/
University of Michigan’s MPulse: https://smtd.umich.edu/engagement-outreach/youth-programs/mpulse/
Carnegie Mellon Summer Precollege Drama: https://www.drama.cmu.edu/programs/summer-pre-college/
NYU Tisch Summer High School Drama: https://tisch.nyu.edu/special-programs/high-school-programs/drama
AUDITION PREP PROGRAMS TO START WITH:
⭐️⭐️Summer University Theatre Experience: https://summeruniversitytheatreexperience.com/ ⭐️⭐️
Artsbridge: https://artsbridge.com/
Here's a picture of me with some of the friends I made at the Summer University Theatre Experience! I'm still close with many of them, and they've all gotten into really incredible schools!
Also, because I am an avid screenwriter, I also took a summer program at Loyola Marymount University for their Screenwriting BFA! Even though it wasn't theatre related and I didn't end up committing there, I still had an amazing time.