Visas
Most nationalities need a visa arranged in advance through a Chadian embassy. The process can be slow, so apply well ahead of your trip. Bring multiple passport photos. A letter of invitation or hotel booking may be required. Visa-on-arrival exists in theory but should not be relied upon.
Money
The currency is the Central African CFA franc (XAF), pegged to the euro at 1 EUR = 655.96 XAF. Cash is king. ATMs exist in N'Djamena but are unreliable and often empty. Credit cards are accepted almost nowhere outside a handful of upscale hotels in the capital. Bring euros or US dollars and exchange them at banks in N'Djamena. Outside the capital, there is essentially no banking infrastructure. Carry enough CFA francs for your entire trip into the interior.
Language
Chad has two official languages: French and Arabic. French is the language of government and education and is widely spoken in the south and in cities. Chadian Arabic is the lingua franca across much of the country, especially in the north and east. More than 100 other languages are spoken. English is of very limited use; you will need at least basic French to get by.
Safety
Chad is a genuinely dangerous country for travelers. Armed robbery, carjacking, and kidnapping occur, particularly outside the capital. The UK, US, and Australian governments all advise against travel to the northern provinces (Borkou, Ennedi, Tibesti), the Lake Chad region, and areas within 30 km of all borders. Even N'Djamena sees periodic unrest and violent crime.
If you travel here, go with an experienced local guide or tour operator. Do not travel at night. Keep a low profile and avoid displaying valuables. Register with your embassy. Have an exit plan that does not depend on your government evacuating you.
That said, many travelers visit Chad's highlights, particularly the Ennedi and Zakouma, without incident, by traveling with reputable operators and following security advice.
Communications
Mobile coverage exists in N'Djamena and larger towns (Airtel and Tigo are the main providers), but drops to nothing in remote areas. Internet is slow and unreliable. If you are heading into the Sahara, a satellite phone is essential. Buy a local SIM card in N'Djamena.
Health
Chad is a malaria zone. Take prophylaxis, sleep under a treated mosquito net, and use repellent. Yellow fever vaccination is required for entry. Bring a well-stocked first aid kit. Medical facilities are extremely basic, even in N'Djamena. Serious medical conditions require evacuation to Europe or Nairobi. Make sure your travel insurance covers medical evacuation.
Water is not safe to drink anywhere. Use bottled or purified water only. Do not swim in freshwater lakes or rivers due to the risk of bilharzia (schistosomiasis).