The "No" Word
This is one all parents including myself have struggled with but as an early childhood professional have learned to retrain myself. Listen to how you speak to your child. How often do you say the "no" word? Do you find yourself yelling a lot? I'm sorry to tell you this, but your children have become accustomed to this and have tuned you out. First, you need to retrain yourself and then in the process, you will find your children will be retrained. Begin by lowering your voice. I know, you are going to say, they can't hear you. That's the point. They will have to lower their's to hear you. Actually, go to your child and at their level - eye-to-eye; speak to them in a quiet voice. They look away; tell them you need to see their eyes. This shows them you respect them. Soon, you will find you will not have to yell to get their attention.
Also, how often do you say "no"? Try rephrasing your sentence by leaving that word out. Instead of no running in the house - how about, walking feet, please. Instead of yelling ask them to use their inside voice (this goes for inside the car, also). This also takes practice. Save the "no" word for extreme danger and safety. This way when you actually need it; they will listen.
Good Luck and this is an ongoing practice/training.