Hello! It sounds like you're planning an exciting trip to Tunisia. I can certainly help out with some travel tips!

Best Time to Visit:
The best time to visit Ghar El Melh, Bizerte, and Tabarka in Tunisia is from April to June and from September to November. During these periods, the weather is mild and conducive for sightseeing and beach activities.

Route and Accessibility:
The most common route to reach these destinations is by flying into Tunis-Carthage International Airport. From there, you can hire a car or use public transportation to reach Ghar El Melh, which is about an hour's drive away. Bizerte is about another half hour from Ghar El Melh, and Tabarka is about a 2.5-hour drive from Bizerte.

Accommodation and Booking:
These cities offer a range of accommodations to suit various budgets. It is advisable to book your accommodations in advance, particularly if you're visiting during the peak seasons. Online booking platforms and travel agencies can be useful for finding suitable accommodations.

Clothing and Essentials:
Light, loose clothing is recommended due to the Mediterranean climate. Don’t forget your swimsuit if you plan to enjoy the beaches. Also, a hat, sunglasses, and sunscreen will provide protection from the sun. Consider packing a light jacket or sweater for cooler evenings.

Health and Safety:
Ensure you're up-to-date on routine vaccines before your trip. Tap water is generally safe, but bottled water is recommended for those with sensitive stomachs. Be cautious of your surroundings and beware of petty crime like pickpocketing, particularly in crowded areas.

Local Etiquette and Respect:
Tunisians appreciate polite manners. It's polite to greet people with 'As-salamu alaykum' (Peace be upon you). Dress modestly to respect the predominantly Muslim culture, especially when visiting religious sites.