Visas. Most nationalities need a visa. Citizens of many countries -- including the US, UK, EU, Australia, and Canada -- can buy a visa on arrival at Cairo airport for around $25, or apply for an e-visa in advance at visa2egypt.gov.eg. The standard tourist visa is valid for 30 days. If you are entering only the Sinai (Sharm el Sheikh, Dahab, St. Catherine's), you may get a free 15-day Sinai-only permit instead, but this restricts you to the peninsula.
Money. The currency is the Egyptian Pound (EGP or LE). ATMs are widely available in cities and tourist areas. Credit cards are accepted at hotels, upscale restaurants, and shops, but Egypt is still largely a cash economy -- carry small bills. The pound has devalued significantly in recent years, making Egypt very affordable for visitors with foreign currency. Tipping (baksheesh) is a way of life. Tip hotel porters, restaurant servers, bathroom attendants, and anyone who helps you at a historical site. Small amounts are fine -- 10-20 LE for small services, 10-15% at restaurants.
Language. Arabic is the official language. Egyptian Arabic is its own distinct dialect, widely understood across the Arab world thanks to Egyptian cinema and music. English is spoken at hotels, tourist sites, and by many young Egyptians in cities. French is less common than it used to be. Learning a few Arabic phrases goes a long way -- "shukran" (thank you) and "inshallah" (God willing) will serve you daily.
Safety. Egypt is generally safe for tourists, and the government takes tourist security seriously -- you will see tourist police everywhere. That said, petty crime exists, and the hustling at major sites (especially the Pyramids) is intense. Remain firm but polite. Avoid large political demonstrations. Women traveling alone will likely experience harassment, particularly verbal -- dressing conservatively helps but does not eliminate it. The Sinai has seen security incidents in the past; check current travel advisories for areas outside the main resort towns. The Nile Valley and Red Sea coast are well-traveled and safe.
Health. Tap water is not safe to drink -- stick to bottled water, which is cheap and available everywhere. Avoid uncooked vegetables and salads from street stalls until your stomach adjusts. Pharmacies are well-stocked and medications are cheap. No vaccinations are required for entry unless arriving from a yellow fever area, but hepatitis A and typhoid vaccines are recommended.
Electricity. 220V, European-style two-pin plugs (Type C and F).
Internet. Mobile data is cheap. Buy a local SIM card from Vodafone, Orange, or Etisalat at the airport or any phone shop -- you will need your passport. WiFi is available at most hotels and many cafes.