While no attempt to learn is ever completely error-free, we can of course tailor learning sessions for our dog to be error-less. This means we structure the learning in such a way to help them be MORE LIKELY to succeed, even to the point where it seems so simple anyone could get it right.
Why make it so simple? Because knowing how to solve a problem or do the right behaviour BUILDS CONFIDENCE. If I were to ask you to solve a complex mathematical problem (without a calculator) and your knowledge of math is limited to the basics you would struggle or fail to make any headway. This would leave you feeling useless and frustrated. You would likely give up even if I told you there was a candy bar for a reward.
Dogs learn from success very well. They don't need to fail in order to learn. In fact, since we can't explain to them what they did wrong, it is just confusing and frustrating. So why should we allow our dogs to feel this way when we know there are better ways to learn and grow skills?
Things you can do to help your dog succeed:
Teach new behaviours in LOW DISTRACTION environments, where they are MORE likely to focus and LESS likely to be distracted by people, animals and smells.
Work in small steps moving in the right direction of the final behaviour. It doesn't need to be the entire problem solved in one go.
Set up for success! Remove or distance yourself from distractions when first working on a new skill.
Focus on your dog! If you are distracted when training, your dog will likely be distracted too.
Reward your dog with the things they want most for doing the things we are asking of them. The value of the reward makes a difference in the performance of the behaviour. If you reward with low to no value you will not build a behaviour any time soon. Keep in mind it is your dog that determines what has value to them and this may change from one moment to the next.
Work in short training sessions of about 2 minutes so you don't frustrate or nag at them!
Be patient, they are thinking creatures that DO NOT SPEAK ENGLISH. It may take them a little bit of trial and error to figure out what we want.
Once they understand the skill, generalize the behaviour. Work in one room, then another, then your back yard, front yard, down the street, at the park etc. This means they can learn to produce the skill anywhere and under different levels of distraction. But it takes a little time to build up!
The key is to be a little more understanding and help your dog to succeed. The more they succeed and are rewarded for their success the stronger and more reliable the behaviour you are training will be.