Sure! A trip to Shiraz, Tehran, and Isfahan will take you through the heart of Persian culture and history. Here are some tips for your journey:

Best Time to Visit:
The Spring (March to May) and Autumn (September to November) would be good times to visit these cities, as the weather is mild and comfortable.

Route and Accessibility:
Tehran has two international airports, the Imam Khomeini International Airport and the Mehrabad Airport. From there, you can take domestic flights or bus/train rides to both Shiraz and Isfahan. Isfahan and Shiraz also has international airports.

Altitude and Acclimatization:
These cities aren't at extremely high altitudes so altitude sickness won't be a major concern. However, if you're planning on exploring the mountain regions, make sure to acclimatize yourself first.

Accommodation and Booking:
It's always a good idea to book your accommodations, tours, and sightseeing venues well in advance, especially during peak tourism times. There are plenty of options ranging from budget hostels to luxury hotels in all three cities.

Clothing and Essentials:
Remember that Iran follows strict dress codes especially for women. Women need to wear a headscarf and loose clothing that covers their body. Men should avoid wearing shorts and vests. Also, pack essentials like sunscreen, hats, and sunglasses as the sun can be quite harsh.

Health and Safety:
Drink plenty of water to avoid dehydration. Also, ensure that your vaccines are up-to-date. Follow the local law and regulations for safety purposes.

Local Etiquette and Respect:
Iranians are known for their hospitality. When in Iran, try and learn a few basic Persian phrases, respect local customs and dress codes. If you're invited into an Iranian home, it is customary to bring a small gift.