I've always pronounced the word "Southern" to rhyme with howthurn. I know most people say it like "suthurn" instead. I didn't realize that the way I pronounce it is considered weird until recently!
We'll usually understand if you get it wrong. There's a lot of extremely counterintuitive ones. If you're American, the most likely trap is Edinburgh - it's not EE-den-berg, it's EDD-in-buh-ruh or EDD-im-bruh.
I'll also just have to ask that the same grace is returned when I inevitably fuck up basically any place name based on anything Native American, because I don't know how any of those languages work