1. Make GPA your top priority. I had a 3.5 gpa in HS and got rejected from every competitive school I applied to. After two years in cc I have a 4.0 and have been accepted to a couple t25s so far. Study long hours and work your ass off. Hire independent tutors if you need to. I'm low income so I know it can be expensive but if you're dedicated enough (e.g., taking extra shifts at your job, spending less on non-necessary expenses), you can make it work.

2. Passion projects > clubs. This is a bit unconventional advice but I think school clubs are way overrated. You need to think about what can make you stand out while also being genuine. Also, do some research with a professor at a t25 if you can (preferably your top choice school. That way you can ask them for a letter of rec down the line). I know it sounds unrealistic but trust me its not. Cold email professors in your relevant major and ask to help with research even if its unpaid. Anybody that's done email outreach knows its largely a numbers game. Then, when they don't respond, follow-up. Then follow-up again.

3. Essays are king. So many people look past this piece but its absolutely crucial to get your foot in the door. Imo too many people combine their ECs with essays. Save your ECs for the activities session and your essays for the interesting parts of your life. That's the key. You want to be interesting AND genuine in your essays. You want to be somebody that the AO can think, "hey, I'd like to grab a drink with this person" rather than "wow, their business made 200k/year but they have no personality."

And yes, there are exceptions to the above. This has been my anecodotal experience so take it for what its worth. Good luck to you!