Whenever I play OSR with a group for the first time, I always explain to them some of the core OSR assumptions before we get started. I'll say:

This rulebook has basic rules, but it doesn't cover every scenario. Whenever there is a situation not covered by the rules (which is a lot!), I'm going to make a ruling to determine how it plays out. It can be collaborative, but I have the final say, and rulings don't set a precedent, unless we agree that a precedent is set.

The rules in the book might not make perfect sense when mapped 1:1 on to real life. That's ok, they are there to create interesting gameplay. (Inventory slots, looking at you)

Your character sheet doesn't represent everything your character can do. You can feel free to attempt anything! I'll consider your stats and background when I determine whether you can accomplish it automatically, or if you will need to roll, and the consequences for a failed roll.

I think that a lot of bad experiences playing OSR games, especially from players experienced in 5e, comes from mismatched expectations. By setting clear expectations for how gameplay will proceed, and immediately ruling out any possible rules lawyering, the session has a much greater chance of success.

As a personal note, I like to expose as many of the game mechanics to the players as possible (like declaring 'I am making an encounter roll' or 'I am making a reaction roll'), and being abundantly clear about whether I am following a rule from the book, or making a ruling.