Most toddlers fall into the no trap since it's easy to say and is likely one of the very few words they know. Help her to find alternatives to no and try to keep her life as predictable as possible to avoid meltdowns. Your toddler knows that you're running the show; all she wants is a few minutes in the director's chair to feel like she's in charge sometimes.
Turn those noes into yeses
Give her choices
Instead of: "We have to leave the playgroup now."
Say this: "Pick one more toy to play with before we go."
Avoid yes-or-no questions
Instead of: "It's time for your bath. Are you ready to get into the tub?"
Say this: "Do you want to use bath crayons or bubble bath?"
Limit your use of "no"
Instead of: "No, we can't go to the park. It's raining."
Say this: "Did you see those blocks? Let's play with them instead."