Strangers meeting at a bar is our go-to. We get dressed separately, meet at an actual bar, and act like strangers for an hour first. The slow build of 'meeting someone new' is worth the effort every single time.
For beginners: don't overthink the costume. A simple premise works far better than an elaborate setup you'll both feel awkward in. Start with a role, not a full character. Keep it light.
Teacher/student and boss/employee scenarios work really well because the power dynamic is clear and easy to play with. The key is having a safe word so both people actually relax into it.
Tip from experience: plan it in advance rather than springing it on your partner. A 'want to try something Thursday night?' text with a loose idea lets both people get into the mindset and actually enjoy it.