It’s far more effective to tell your toddler what he should do than to say what he shouldn’t do. It’s no fun being constantly told: “Don’t do this! Don’t do that!” No wonder he’s always moody and uncooperative.
For example, instead of telling him “Don’t leave your toys all over the floor”, rephrase it as “Do keep all your toys tidy in the toy box when you have finished”. Rules expressed positively creates a relaxed atmosphere at home.