Don t drink openly in the streets, always do it in a designated place such as a bar, disco, or your own place. Do check for expiry dates, some beers and wines are long over due. Do carry a water bottle with you, at all times, on any trip. Especially when visiting in summer. Don t drink tap water, even though it is clean and all Egyptians are used to it you will take a few days of stomach aches to get aquatinted.
Mineral water is available everywhere.
Don't smoke, drink or eat in public during the month of Ramadan, during day-time. Do take it slow on eating fuul and falafel or koshary. You might get some tummy aches for a while until you get used to it. They re all perfectly clean but a little too heavy for digestion compared to western food. Ladies, Do wear swimming suites on beaches, but a quick glance at the people around could be helpful at first.