Hello
It's always good to be sensitive to local customs and I would recommend dressing fairly modestly. Egypt is an islamic country and attitudes to clothing tend to be fairly conservative.
Men should wear long shorts or lightweight trousers and short-sleeved shirts or t-shirts.
Women should avoid displaying too much flesh as this can attract unwanted attention. Lightweight, loose-fitting clothes are the best solution.
Women only really need to cover their hair if visiting mosques. This isn't usually necessary at the ancient Egyptian sites, though it also helps to keep the sun off your head anyway.
Kind regards,
Olly, your editor