Sure, visiting Zaragoza, Teruel, and Huesca in Spain is a great decision due to their rich history, culture, and pleasant weather. Here are some travel tips:

Best Time to Visit:
The best time to visit these places in Spain is generally late spring (April to June) or early fall (September and October). During these periods, temperatures are usually mild and there are fewer tourists.

Route and Accessibility:
You can reach Zaragoza easily by train or bus from Madrid or Barcelona. From Zaragoza, there are regular trains and buses to both Teruel and Huesca. Local public transport in these cities is also efficient and reliable.

Altitude and Acclimatization:
The altitude is not high in these areas, so there are no specific precautions necessary about altitude acclimatization. However, always ensure to keep yourself hydrated.

Accommodation and Booking:
Pre-booking is advisable if you are planning to visit during the peak season (July-August). Accommodation ranges from budget to luxury hotels. Apartments or homestays are also available.

Clothing and Essentials:
Pack according to the season. In summer, light clothing is essential with sunscreen, hat, and sunglasses. However, during winters, it can get quite cold, so warm clothing is necessary. Always carry a good pair of walking shoes, as these cities are known for their beautiful old towns which are best explored on foot.

Health and Safety:
Spain has some of the best healthcare systems in the world. Pharmacies are easily available everywhere. No specific vaccination is needed. However, on the safety side, be aware of your belongings as pickpocketing can be an issue in tourist spots.

Local Etiquette and Respect:
These regions of Spain are renowned for their cultural history and traditions. Try to observe local customs and meet locals with respect. When visiting any religious spots, ensure to dress respectfully. Learn basic Spanish phrases to help interact with locals.