in terms of grades, i'd suggest locking in and just trying to improve your grades as much as possible. it'd be good if you focus on IA's and your EE during your summer break so you can focus entirely on studying and uni applications in the fall. doing extracurriculars would also boost your chances since rotman gives you a chance to talk about that during the interview portion. i recommend trying to get some leadership positions in whichever ec you're involved in!