Activity for Catherine

So my wedding is tomorrow and the only thing left to figure out is tipping the reception place (not outside vendors). The contract suggests 20% gratuity but my dad says you do it per server and then based on their service just like another...

I need help with something that I didn't think would be a big deal. My bridesmaids will be wearing royal purple dresses, knee length and all the same style. I really didn't care about the shoes just figured they should at least all wear the same...