Because the US college application process is unique, long, and nuanced, you will need to constantly research at every step. This is a very important skill to learn for all applicants. Whenever you have a question about anything, your first instinct should be to look it up on the internet. The first and the most important source should be official websites. YouTube and Reddit are unmatched resources when it comes to US college admissions. We will also link some other credible sources that we recommend checking out.
If you're having difficulty with anything at all related to college admissions, this subreddit has something to help. It features comprehensive guides, latest updates, active discussions, and much more. This should be a go-to for any problems you run into.
This one is for resources and advice related to SAT General.
This one is for resources and advice related to AP tests.
This has specific advice for international students.
This one is for resources and advice related to the TOEFL.
There are several high-quality YouTube channels run by successful students, colleges, and admissions experts which you can consult. Some of these have been linked below.