Role play advice/help

My wife (37) and I (38M) have done some minor roleplay in the past. Strangers at a bar, pilot/flight attendant and while it’s been very enjoyable, we always broke character pretty quickly and just went about our business.

Recently after a crap couple of days of work for her I jokingly said “sounds like you need to be the bitchy boss and settle this. Wanna try practicing with me?”

To my delighted astonishment she agreed and the costume is in the way.

Now here is where I need some advice. She’s never taken on the brash role or been ‘in charge’ before and since she so quickly agreed I really would like some tips for myself to get into/stay in character and thoughts/ideas for her as well so she doesn’t break character as well? Not looking for real BDSM type of advice but just thoughts that she can use to be more assertive/in charge. Thanks!