Give the restaurant an accurate party size
State the date, arrival time and confirmed guest count. Ask whether the group can sit together and whether there is a deposit, set menu or minimum spend.
If the number changes, update the restaurant before arrival rather than hoping extra seats will appear.
Discuss food requirements directly
Ask guests to share relevant requirements privately, then discuss them with the restaurant. For allergies, the diner should confirm suitability directly with staff; don't make assurances on the venue's behalf.
Check whether advance ordering is needed and when the kitchen can serve the group.
Agree on paying before the bill arrives
Decide whether people pay separately or one person settles a shared amount. Ask the restaurant whether it can accommodate that arrangement. Make optional orders the responsibility of the person placing them unless the group agreed otherwise.
Save the restaurant in your outing plan with the reservation name and arrival time. Keep enough space after a tour that a small delay doesn't cause the whole table to miss its booking.
Rules, fees and opening hours change. Confirm anything that matters before you rely on it.