Maybe it's obvious but I found a cool way to farm experience and items from the beginning on. When you have defeated female enemies, don't hide them in boxes immediately. Gather them together somewhere on the map and lure the next enemy to your gathering spot before attacking her. This way, the prisoners will be drawn into the fight but remain tied up, you only have to defeat the new enemy before anyone can get free. But you'll get easy experience, gold and items drops from the prisoners, too. Repeat until you've captured everyone. If you exit the screen or enter a tent without putting the captives in boxes, they will be free again and you can do the whole thing over again. If you do this in a spot where defeat doesn't get you an instant game over, just surrender when you run out of CP. You'll be fully rested and only have to free yourself from your restraints, which is way faster and more fun than returning to an inn if you don't want to waste healing items. And it'll raise your escape level, too.
To the developers: Please don't "fix" this, maybe it's abusing the game system a little, but I've been doing that for hours and it really makes the game fun to play that way. It would make the game much shorter and less enjoyable if the player couldn't to that anymore (e.g. by doing away with free healing when being captured). The way it is, I can get most out of the combat and escape system and fully enjoy the game instead of speedrunning it.