Do all the topics and strengthen beforehand and then place in gaps of knowledge on the cheat sheet. Cheat sheets might not do much tbh since it's Maths but since you can bring one in might as well use it I guess.
It's not too bad honestly, lived around the area for a while. Most of the dodgy places are near the train station and shopping mall. Suburban streets not really. Just using common sense and taking some precaution is enough
Heard from my friends it's a really bad school, they hate it because everyone is "stupid" and is not really catered toward sciences but more into humanities. Not sure why you're eager to get into a rank 300 school either lol, try for selective. Amazing competition.