Sure! I'd be happy to provide some travel tips for your visit to Valletta, Senglea, and Cospicua.

Best Time to Visit:
The best time to visit Valletta, Senglea, and Cospicua is during spring (April to June) and autumn (September and October). These periods provide pleasant weather conditions perfect for sightseeing and outdoor activities.

Route and Accessibility:
These locations are all in Malta and can be reached via Malta's International Airport. Buses, taxis, and ferries are available for traveling between these cities. A popular option is the ferry service between Valletta and the Three Cities (Cospicua, Senglea, and Vittoriosa).

Altitude and Acclimatization:
As Malta is an island nation at sea level, you do not have to worry about any high-altitude issues.

Accommodation and Booking:
Valletta offers a range of accommodation from luxurious hotels to budget hostels. It's recommended to book in advance, especially during the peak tourist season (summer months). Senglea and Cospicua also have a good selection of accommodations.

Clothing and Essentials:
If you're visiting in the warmer months, bring light, breathable clothing, sun protection, and comfortable walking shoes. During the cooler months, warmer layers may be necessary, especially in the evenings.

Health and Safety:
Be sure to stay hydrated, especially during the hotter summer months. If you're visiting any beaches or planning water activities, remember to stay safe and follow any local guidelines regarding water safety. Consider purchasing travel insurance for emergencies.

Local Etiquette and Respect:
These cities have a rich history and cultural heritage. Be respectful of the locals and their customs. When visiting churches or other religious sites, ensure to dress modestly.