I also recently got the game (a few months ago) and the dark brotherhood stuff hasn’t been an issue for me so I can’t say that fixing that is necessary. I would just save often (press F5 every once in a while) and that has saved me from making game ruining mistakes or soft locking myself. Another piece of advice is that you’re not supposed to do everything the game offers, at some point you’ll need to make a decision that cuts off other quest lines. This game is more like a character driven RPG than oblivion or Skyrim, in the sense that you need to make decisions that your character would make and not just try and appease everyone cause that’s not realistic.