1. Learn From Your Mistakes

If you roll a natural 1 and fail the roll, you gain inspiration. Natural 1s don't hurt you (aside from failing the roll), you don't drop your weapon or hit an ally or anything like that.

2. Non-combatants Are Safe

If you get into a fight, it's assumed that pack animals and pets get out of the way and won't be attacked. As long as you don't involve them in the combat, like telling your dog to attack the goblin, it will be fine.

This also applies to commoner servants and things like that, unless it's for story purposes. An enemy might take an NPC hostage, and if you're in a town with a lot of peasants they might get attacked/killed as part of a storyline, but given the choice between a wizard shooting fireballs, a fighter in plate mail, and the cook cowering next to the horses, enemies are going to go after one of the people actively attacking them.

3. Maybe More Fun Rules

That's all I can think of for now, but I reserve the right to add more as time goes on. These are meant to make the game more fun though, not hurt players.