What words do you use with your dog and how did you teach them what they meant? Dogs are not verbal creatures (which explains why I love them) so teaching meanings usually involves some sort of activity to link it to. Sit, down, off, heel, come all have a basic meaning and how we define them is how the dog learns what they mean.

If I am teaching a dog to heel then I need to make sure they understand that it means (to me) to walk as close to my side as possible without interfering with my walking with your eyes even with my leg. That never varies. Next time I work with the dog, heel will mean....see above definition. Sit means put your butt on the floor immedietly. Once again that will never change.

How do I teach my dog what I mean by No or if they are being good? I use specific words ("very good") when I praise my dogs coupled with physical contact that they really like. That defines the words. For "No" I will use a firm touch or a leash pop coupled with the word to define it as stop what you are doing. I don't get into the "no bite", "no jump", etc. No just means stop whatever you are doing. I am never angry with a dog when I need to stop them from doing something since it is a reflection of what I have taught so I say it in a calm, firm tone of voice.

The only time I get emotional in my training is my praise. That way I can show I'm very pleased with what they are doing. Anger and yelling only lead to fear while calm and consistent contributes to learning.

Always think about how you define your words and be consistent with their use and their meaning and your communication with your dog will be much easier.