How do I create a useful learning objective? I am preparing a lesson plan and I unable to write objective of this session in a correct way. 

My question is how do we state objectives of sessions such as:

1- Avoiding common mistakes in Email
2- Avoiding common mistakes when meeting someone for the first time
3- Avoiding common mistakes in writing 


They all have one objective and that is  how to avoid common mistakes(and save yourself from jeopardizing your career, for example in case of emails). 

I want to understand how do we present this objective to the audience or students. 

My attempt is something like this:  

At the end of the session the participants would be able to understand how to avoid common mistakes in email communication that can lead to serious issues 

But I am not very please with this statement. Really appreciate your help in drafting a good objective phrase.
Disclaimer: Mostly opinions.

First. I'd suggest perhaps one level down in terms of the verb choice. What the course will likely do is to introduce an array of possible mistakes in these activities so that audience can avoid committing them. So, the objectives should not be "avoiding" but rather along the line of "familiarize with", "able to list", or "be introduced to a survey of." Whether to avoid or not is really not the takeaway.

The general tip of writing objectives is to think: "If I am going to assess whether my audiences have learned my messages, what are the aspects I will be testing?" Very likely, you are not going to give them a mistake-prone situation and see if they avoid it in real life; but perhaps provide a list of scenarios and see if they can identify which one is likely going to cause a mistake, and which is a safer/more professional approach. In other words, you'll be testing their knowledge and attitude, and not their behavior after class. Yet. your current objectives are about their behaviors.

Second, perhaps add some specificity. E-mail for what? Talking to family members? Someone whose pets just died? Business? Potential dates? If someone just picked up this one page of objectives, is there enough information for the person to decide if he/she should consider your course offer?

Third, consider providing a clear set of general benefits. After learning all these objectives, what will likely happen? Will they have a better commands in communicating with people in professional setting? In other words, what are the aspirations of your course, that you won't be teaching directly, but the audience may be able to realize that if they follow your advice?

Meanwhile, beware of over-promising. Communication is at least a two-way process and even your audience did everything "right," mistake may still happen. I'd suggest perhaps more neutral wording such as "achieve high level of clarity..." so as to "minimize potential miscommunication or mistakes."