behavioural management

Hi all, I'm a young Pre-school teacher , I am currently pursuing my degree in Early Childhood Care and Education and Family Studies which is a challenge, but i am pressing on none the less because i enjoy the field that I am in and I welcome any assistance that can aid me in becoming as efficient and proficient in it that I can possibly be. Can anyone offer advice on how to deal with behavioral issues in the classroom such as, aggression, tantrums,separation anxiety etc.?