Sure, I'd be delighted to help you plan your trip to El Haouaria, Kélibia, and Menzel Bourguiba!

Best Time to Visit:
The best time to visit these Tunisian cities is from April to June and September to November in order to enjoy the mild Mediterranean weather. The summers can be hot, especially in July and August.

Route and Accessibility:
The nearest airport to these destinations is Tunis-Carthage International airport. From there, you can hire a taxi or rent a car to reach these cities. It's a good idea to have a local map or GPS for easier navigation.

Accommodation and Booking:
There are several hotels and vacation rentals available in these cities. It's better to book your accommodations in advance, especially during the high season. Sites like Booking.com or Airbnb can be useful.

Clothing and Essentials:
It's advised to dress modestly as Tunisia is a predominantly Muslim country. Warm weather clothing is sufficient for most of the year, but do pack a sweater or jacket for cooler evenings. Don't forget your sunscreen, sunglasses, and a hat for sun protection.

Health and Safety:
Standard vaccination is required before travelling to Tunisia. It's also advised to have travel insurance. In terms of safety, always be cautious of your belongings and stay careful in crowded places.

Local Etiquette and Respect:
Tunisians are known for their hospitality. Always remember to respect local traditions and customs. It is customary to say 'As-salamu alaykum' (Peace be upon you) as a greeting.