I have an flag quiz app on my phone that is really good at teaching you to not only know the flags of the world, but also their geography. I recommend having something like that for anyone who wants to improve the basics of their world geography. Honestly, I'd recommend it to everybody because it is a fun way to learn something that may or may not be useful in the future.

I'm not great at geography myself so it was a way for me to work on a weak spot and having fun doing it. Only thing my flag app doesn't really cover is states in America and Germany etc. so I don't have a lot of practice in those. I can sorta place the states of Germany but the United States is still kinda abstract to me.