As a GM in old school games, you have to come up with answers to questions that aren't covered by the rules. I think this is one of the strengths of using a rules-lite game such as Labyrinth Lord because you can craft the game to your likes very easily, by adding on small layers of complexity as time goes on. It just feels organic somehow, like the game is slowly growing.
As a GM I always want to be fair and consistent. So to make sure that happens, I've been jotting down the rulings I've been making as we play. This way I can keep my own past rulings straight, and the players feel like they have a consistent and fair interaction with the rules and past precedents. These rulings can also be called house rules if you like, and I think it is always important that your players know what house rules you have come up with for your games. I always try to give my players a list of house rules before we even start playing, but some of them creep up after you start.
So, if you are a GM out there, make sure to keep a list of what makes your game different when it concerns the rules, and I think your players will greatly appreciate you being organized and fair.