In the case of digital marketing, the theories which you have learned cannot be smoothly translated into successful action. You may have a clear route map as to how your digital marketing campaigns must run. But one cannot expect that you will cover everything perfectly until you build and test the campaign appropriately.
In many cases, digital marketing executives may have forgotten to define and include proper personalize, sometimes it may be a wrong image to represent the values or some dynamic content creation without giving it a proper thought. It may also be leaving out an important link, making a mistake on alt text, and could be million other things too. A skilled professional will try to get everything done perfectly from the very beginning. But still, we cannot bypass the need for a thorough review of the completed works.
To ensure baseline perfection, you need to test the below areas at least:
Appearance and layout of your messages on different devices
Spelling and grammar of the messages.
All the links to ensure that they are pointed to the right location and also that those work well
Proper link placement in emails and other places.
Correct usage of name & address for messages.
Defining apt audience for the messages
For this, you should develop a custom checklist of all the basic elements to be tested. Beginners can use this list as a reference and keep on adding/modifying it over time. Testing may be time-consuming initially. But it can surely save a lot of time and effort for you compared to leaving it unattended and trying to fix the errors later.