First, know what is "investment grade"
Second, earn as much as you can to invest in "investment grade"
Then, look for "investment grade" stocks.
I do believe the process involves "continuous lifelong learning" and therefore we all keep reading and read source of information, if no time for other information, at least the annual reports and the quarterly results.
I subscribed to tool that helps me to speed up the process, if you keen to know what it is, click here.