Hello, it sounds like an exciting trip to Iran you're planning. I'm glad to provide you with some helpful travel tips!

Best Time to Visit:
The best time to visit Iran, and specifically cities like Kashan, Shiraz and Mashhad, is during spring (March to May) and autumn (September to November) when the weather is mild and the landscapes are beautiful.

Route and Accessibility:
The most common way to arrive in Iran is by plane. Numerous international airlines fly into Tehran's Imam Khomeini International Airport. From there, you can take domestic flights or trains to Kashan, Shiraz, and Mashhad. You can also rent a car or take buses which are an affordable and convenient mode of transportation.

Accommodation and Booking:
There's a wide range of accommodations available from luxury hotels to budget guest houses. It's always best to book in advance. Online platforms such as booking.com or local travel agencies can help secure reservations.

Clothing and Essentials:
As Iran is an Islamic country, it's important to dress modestly. Women should wear a headscarf, long sleeves, and long skirts or pants. Men should wear long pants. Light, breathable fabrics are best due to the warm climate. Don't forget your sunglasses, sunblock, and a good pair of walking shoes.

Health and Safety:
Ensure your routine vaccines are up to date. Tap water isn't generally safe to drink, so stick to bottled water. Public transportation and roads are generally safe, but traffic can be unpredictable, so be cautious if you plan to drive.

Local Etiquette and Respect:
Iranians are known for their hospitality and respect etiquette. When visiting religious sites, be quiet and respectful. It's common to greet with a hand over your heart rather than a handshake. Remember to ask for permission before taking pictures of people or religious sites.