People Don't Praise Their Dogs Enough
Sometimes it's really hard not to generalize, but I do feel the need to generalize right now by saying, "People don't praise their dogs enough!"
I find that people are much more likely to admonish their dog for doing something deemed to be 'wrong', than praising their dog for showing desirable behaviour or doing something 'right'. Sadly, that just seems to be human nature.
Regardless, how is your dog going to figure out that she did well (and that you'd like her to keep doing that good thing) if you're not providing a positive response?
Praise To Reinforce Desirable Behaviour
Let's say your dog successfully learned a new cue or skill, but over time you start to wonder whether she actually learned it at all because she's becoming increasingly inconsistent with it. One of the most common mistakes people make with their dogs is to think that once the dog has been 'trained' to do something, that the dog is now set for life. This couldn't be further from the truth.
Now I'm not suggesting that you need to dedicate big chunks of time each day for the continuation of formal training, but I am suggesting you should positively reinforce your dog's appropriate and desirable behaviours whenever you experience them.
For example: How hard is it to give your dog a "Good girl!" when you ask her to "wait" or "leave it" or follow a variety of other everyday cues? How difficult is it to give her an appreciative stroke down her flank after she waited patiently and politely for you to pay the pizza delivery person at the door?
Think about it - the more your dog learns how rewarding it is to display certain behaviours, the more she'll want to continue displaying them for you. It's even more effective if your dog can't predict the type of positive reinforcement you provide, so mix up the 'rewards' you give her: Spoken praise, a warm and friendly smile, a scratch behind the ear, a treat, playfulness, etc.
Ongoing positive reinforcement isn't physically hard at all... it just takes some mental discipline on the part of we humans so it can, over time, develop into a habit.
And once you get into the habit of ongoing positive reinforcement you'll benefit from the consistency in your dog's behaviour, and the growth in your dog's confidence and trust in you.
Now wouldn't the world be a better place if we humans could get into this same habit of positive reinforcement when dealing with each other!! :)