When creating a character you will have a choice to focus on strength or intelligence or balancing both of those stats. Create a balanced character by keeping your strength and intelligence at similar values. Start with a dorm mate that gives you the largest increase in strength, then get one with biggest intelligence. They will eventually even out. Always purchase the most expensive dorm mates as soon as they become available. After leveling up your early tutors two or three times, evict them. After getting dorm room #10, get rid of your first six dorm mates and replace them with better ones.