Self Study Suggestions to prepare for CS Fall 2025?

Hello, I’m a gap year student applying for CS in Fall 2025

Since I have 9 months until I enter school, I am wondering how I should study computer science until then. Right now I am starting on the foundations course in the Odin Project for reference. Here are my questions:

1. Many students complain about how university math is much harder than high school math so do you all suggest any university math courses and their course codes? 
2. Thoughts on reading through entire CS Textbooks?
3. Any tips for making personal projects?
4. Other suggestions?

I appreciate all insights and suggestions.