Hello from UK.
The Old Testament was written thousands of years ago during the time when Egypt in Northeast Africa was in great power and influenced many civilizations in the world at that time. So in order to understand it better, it would be good to read about major historical events all over the world at that time, then compare and contrast with the scriptures in the Old Testament.
Due to many translations overtime, comparing and contrasting would be a good start point.
Also get a good understanding of 'dates and times' in how time was measured.
Because the Old Testament was written based on Egyptian script and how the Egyptians measured time, it
would be good to get an understanding on their Calendar systems and how they dated time.
Since the Old Testament is one of my passions, I would like to start out by saying a little about dates and times based on my research:
For thousands of years prior to the time the Old Testament was written, the end of the year for the ancient Egyptians was
the month of FEBRUARY.
The scientific New Year for the whole world is based on the Spring Equinox, however due to the leap year system, it varied,
Sometimes the New Year began in the month of MARCH and sometimes on the leap year it was APRIL.
The ancient Egyptians also regarded the stars to date their calendars as well.
But other ancient civilizations such as in Mesopotamia would be vital to understanding the Old Testaments as well.
Because the Old Testaments includes the life of Abra-HAM, who was born in Mesopotamia, this civilization would be important to study to better understand the Old Testament. Also, read up on ancient Assyria as well.
So, I would say read about other secular historical accounts and publications too.