If you want to see my overall impressions of the game and what meta critic is saying about Triangle Strategy click here ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-vvwUvVJURIU.html
This is a nice concise guide and actually spolier-free. If I'm watching your video and you reveal where a specific helpful item is located or how a specific chacter with nice combat abilities will join my party after certain actions are taken...yea I don't consider that 'spoiler-free'
I disagree with tip#2. Your turns come faster if you don't use an action. Will technically make hard battles harder if you do meaningless actions. You can gain exp in mock battles in tip#1 anyway Otherwise good list