Builder choices in Noida Extension, hidden risks?

Okay I'll be honest — I completely underestimated how confusing this process is. We're upgrading to a 3BHK in Noida Extension for the kids, maybe Sector 137 ya Knowledge Park 5 ke paas. My wife's priority is safety and good schools. I'm looking at Gaursons and ACE Group projects, but builder ke hidden charges aur construction delays ka darr lagta hai. Especially after S P Sai IT Pvt Ltd ke issues. How do you guys check for these things before booking? Koi red flags ya legal checks hain jo mostly log miss karte hain?