My first step is to get the right tools for the job. Creating a cover in Word or Paint is the biggest NO NO you can do. It will look amateurish and people will see straight through it.I use Photoshop.
In the beginning allow my mind to wander and consider the out-there concepts I can. In my experience this leads to some cool-ass designs. Once I have had my creative fun, bring it all together and simplify the process.
Consider the Author Brand (what colors do I use, font, style, etc) and most importantly, what can I demonstrate on the cover that shares the entire premise in an instant. This is where I may have the upper hand over a professional.
Once I have a concept you’re happy with, put it to one side and head online. Read sites like The Book Designer and think below:
What stands out?
How do the cover come together?
What role do text and images play?