I get laser hair removal and to prepare you need to shave (don’t wax the day before because shaving still exposes the tip of the hair which is what the laser needs to see) the day before you go or else the laser will hurt a LOT worse than if there was no hair. (without hair its a tolerable pain and not bad at all) But if you forget to shave you don’t have to worry because they always provide razors at the place and shave the area for you but from my experience they always miss spots.. so it’s better to prepare the day before. And yes you can go even though you’ve been waxing but they are going to suggest you not wax after the laser treatment for atleast a few days because the area will be sensitive. You also can’t expose the area to sunlight so if you do your upper lip you’ll have to make sure you don’t have outside plans for the next few days.