When your toddler wants something, think very hard before you say no. If any amount of screaming, crying, moaning, is going to change your mind, then just save yourself the hassle and say yes. Meanwhile, your toddler will learn that when you do say no, a tantrum won't change it.
that's very good advice. it's important to be consistent, so once i say no, i try very hard to stick to that. and sometimes i wished that i had said yes instead.