Of course, here are some travel tips for Skiathos, Skopelos, and Alonissos:

Best Time to Visit:
The best time to visit these Greek islands is from late May to early October when you can enjoy warm, dry weather perfect for beachgoing and water sports.

Route and Accessibility:
All three islands are part of the Northern Sporades island group, the easiest and most convenient way to get there is by ferry or hydrofoil from Volos or Agios Konstantinos on the mainland. For Skiathos, you also have the option of a direct flight from Athens.

Altitude and Acclimatization:
These islands do not have high altitude areas, so acclimatization is not a concern. However, it's always a good idea to stay hydrated, especially under the hot summer sun.

Accommodation and Booking:
Reserve your accommodation well in advance, especially if you're planning to visit during the peak summer months. The islands offer a range of accommodations, from budget hostels to luxury resorts.

Clothing and Essentials:
Pack lightweight clothing for hot and sunny days, a hat, sunscreen, and a good pair of walking shoes. Don’t forget a swimsuit and beach towel. Also, a reusable water bottle could be handy.

Health and Safety:
Always remember to wear sun protection, stay hydrated, and avoid excessive sun exposure during peak hours. Follow local regulations for swimming and boating for your safety.

Local Etiquette and Respect:
Greeks are known for their hospitality. Respect local customs and traditions, especially in more rural areas. When visiting monasteries or churches, dress modestly. In Greek culture, it's also customary to greet people with a warm "Kalimera" (Good Morning).