First of all she should review her cooking skills. If she doesn't feel confident enough she should visit cooking courses, there are plenty of them in every city. Next she should calculate a budget and (optionally) rent a place and hire people. Done. When cooking you should consider amount of waste you will be producing and thus you should double-check your sewerage. Otherwise even your toilet would be clogged often. I would recommend checking pages like this https://sanitaryreview.com/category/how-to/ for reference. I wish you good luck in your affairs!