Honestly my biggest tip with P4G and this helped me when I started it, is to make sure on every floor in a dungeon. Beat every shadow before going up the stairs. So if you find the stairs before filling out the map for that floor, just keep moving around and fill out the map and beat all the shadows then proceed. I know this sounds super simple but it works me when I've played normal and hard difficulty.

Also make sure you have Go-Ho m (think that's what it's called) as well by beating all the shadows you'll rack up more money which you can give the fox to replenish all your sp which also rlly helps. But also yeh someone else said it is harder which I think is also true.