Advice given to me over 20 years ago which helped me a treat
Pick a newspaper, broadsheets are best but not essential, and buy it daily.
Start an A4 diary with subject headings about all the hot topics as of today.
Read your paper from cover to cover each day and update your diary accordingly.
It will take you a good few months to get to the Cranwell stage and by the time you get there you will have a much better understanding with regards to global happenings.
What ever paper you choose learn the names of all the main correspondents as that used to be an all time classic question at OASC