Save During Conversations
In Fallout 4, you should save all the time. You never know when you might run into a problem. You'll also want to save during various conversations you have during the game.
If you encounter colored dialogue option, think about saving because if you fail, you won't get extra XP and you won't gain access to vital information or whatever the NPC is in possession of.
Any time we see a colored response, we save so that we can go back if we need to.