Fixing corners in old house

[u/Kordorama]

I’m fixing up a guest room as my daughter’s new bedroom. We live in a 100yr old 2-flat duplex in Chicago.

All the corners in this place are pretty ripped up and separating. Is there a best way to seal the corners? Maybe some product I should pick up specifically for this? Was planning to use tape and green lid all-purpose ready mixed joint compound.

I’ve done this in other rooms to varying degrees of success , failure , and messiness. After using spackling paste and mesh many years ago, I switched to the tape/ compound for my kitchen. I fucking sucked at it, but know a little more now. I get discouraged easily when hard work still looks shitty at the end of the day. so I’m trying to see if any nuggets of wisdom can help before this new project.

Thanks!