When ordering pizza, remember these things:
- Ask for plates and napkins.
- When ordering, place the tip on the credit card you order with. If you need to adjust it, you can (presumably) do that after the fact.
- Be sure to order beverages, and make sure they come with cups. (Estimate: 10oz == 300mL of drinks per attendee. This is a slight overestimate, but that's fine.)
- Tell the vendor to bring things at least 20 minutes before the actual lunch time, if you have reason to believe that they might slip.