Hi, persistent bridesmaid here.
1. DONT PANIC. It is no longer expected for the brides parent(s) to do active hosting duties regardless of what is written on the invitation.
2. Talk to your daughter!! You will no doubt find she has delegated some of the 'hosting' tasks (moving the crowd around in time for meal, dancing etc) to appropriate members of the wedding party. She will genuinely not be expecting you to do much but smile and enjoy yourself; get her reassurance about that.
3. Don't wear a white dress or an oversized hat. At a formal wedding, no one should remove their hat before YOU do, so your consideration in not wearing it all through the meal will be appreciated by the guests.
4. Nerves and alcohol don't mix. Go very light on the celebrating until after the first course of the meal.
5. Your girl will be nervous about all her arrangements in case something goes wrong. Be a calming presence for her. Offer to run through her checklist and schedule for the day (flower delivery, hair amd make up people etc) with her a few days before so she is confident about when and how everything is happening. Especially what time the wedding cara are turning up!!
6. A chocolate bar before she gets the dress on will be appreciated. Its a long and hungry day for the bride before the meal is served.
7. Keep your happy face on if at all possible - the day will generate enough drama of its own, be the solid and reliable mum.
8. WHATEVER THE DRESS, HAIR, MAKE UP ETC LOOK LIKE, THEY LOOK WONDERFUL AND SHE IS A BEAUTIFUL BRIDE. Yes, this reminder needs to be in caps.
9. The entire bridal party will be grateful for a big packet of elastoplasts if you can fit them in your bag for the day. Sore feet are the devil's own work.
10. Waterproof mascara if you are a crier. I like Dior's New Look in waterproof, unlikely to budge. If you are a real crier, consider an eyelash tint the week before the wedding.
11. The couple and the photographer will already have decided what posed shots they want to be done. Keep smiling and say nothing about this. Photos are a major flashpoint of a wedding day nine times out of ten - everyone is tired, pissed off and hungry by the time they get done and in the UK they are usually also freezing as well. Smile and don't make last minute requests. If you have a particular photo you want taken, let your daughter know this now.
12. Everything about the day is GREAT. The food, the flowers, the service, everything is GREAT. This is not a day to pick holes in stuff beyond your daughter's control.
Good luck and enjoy yourself!!