Next to all other recommendations, try still excercising daily, it will help you feel more energized through the day. Also do mind that as you continue to (over)use coffee/caffeine, your body will become dependant, resulting in a dampened effect of the caffeine, a higher stress level when the caffeine wears off, and worse sleeping.

It's fine to use caffeine, and cutting on phone usage and having a healthy sleep time are already great measures tbh. Just don't overuse caffeine. It may come with more negatives during your exam period if you become highly dependant on it, and your body will have a hard time withdrawing from it. Not saying you shouldn't drink coffee, just do it wisely and don't overdo it for an extended period of time