Sure, these cities have a lot to offer to tourists. Here are some travel tips for your upcoming visit:

Best Time to Visit:
The best time to visit Hammamet, Sousse, and Mahdia is during spring (April to June) and autumn (September to November). These periods offer mild and pleasant weather ideal for sightseeing and beach activities. The summer months (July to August) can be extremely hot.

Route and Accessibility:
You can fly into the capital city of Tunis and then take a domestic flight or a train to Sousse. Hammamet is about an hour and a half drive north from Sousse while Mahdia is a similar distance drive to the south. Car rentals and taxis are widely available but remember that traffic can be heavy especially during peak hours.

Altitude and Acclimatization:
These cities are located at sea level, so acclimatization is not a problem.

Accommodation and Booking:
There are many hotels and resorts to choose from in Hammamet, Sousse and Mahdia. It's advisable to book accommodations in advance, especially during the peak tourist season.

Clothing and Essentials:
Pack lightweight clothing for days when the temperature can soar. A hat, suntan lotion, sun glasses, and beachwear are essential. But remember to dress modestly when visiting places of cultural or religious importance.

Health and Safety:
Stay hydrated and apply sunscreen regularly to avoid sunburn. Familiarize yourself with local taboos and customs, avoid late-night walks in isolated areas, and try to travel in groups.

Local Etiquette and Respect:
Tunisia is a Muslim country, so it is important to respect the local customs and traditions. Dress modestly, especially when visiting religious sites. Consume alcohol discreetly and avoid during the holy month of Ramzan. Don't forget to bargain when shopping in local markets.