Warning - there are no spoilers in my question, but there will probably be gameplay mechanics spoilers in any answers (hopefully).
I'm downloading Lies of P now to give it a shot. I'm not a big fan of RPG elements in these types of games (blasphemy I know), I prefer a focused experience; for example I liked Bloodbourne but never finished it because of all of the options, but I absolutely loved every minute of Sekiro. Basically I can't be bothered with experimenting with builds and crunching numbers, it's not for me.
I know any actual advice will depend on what I want the gameplay to feel like, so I guess all I can say is take Sekiro as an example - I'd probably be focusing on anything that will help speed and parrying (if any stats affect that?) and decent dodging.
So, do you have any advice on things I should focus on, things I should avoid or wait to upgrade, weapons to aim for etc? I don't mind spoilers.
I believe perfect blocks do count towards staggering the enemy. I've put several larger enemies into the stagger state from perfect blocks. I'm running the Motivity build described above and it works great. I will say that dodging and blocking are both very important. Some enemies are better to dodge and some are better to block.