Sure, I would be glad to help you with your trip to Guwahati, Shillong, and Cherrapunji. Here are a few helpful travel tips.

Best Time to Visit:
The best time to visit Guwahati, Shillong, and Cherrapunji is during the months of September to May, when the weather is quite pleasant and is suitable for sightseeing and outdoor activities. Be aware though these regions occasionally experience heavy rain, especially Cherrapunji which is one of the wettest places on Earth.

Route and Accessibility:
You can reach Guwahati by air as it's well connected to major Indian cities. From Guwahati, you can either hire a cab or take a bus to reach Shillong which is approximately 100 km away. From Shillong, Cherrapunji is around 53 km and can be reached by taxi.

Accommodation and Booking:
These destinations offer a range of accommodations from budget hotels to luxury resorts. Online booking sites like Booking.com, Agoda, Airbnb, and Trivago can give you an array of choices based on your budget. Advanced booking is advised, especially during peak seasons.

Clothing and Essentials:
Carry lightweight cotton clothing for the daytime and light woolens for the evenings. Comfortable shoes for walking, an umbrella for unexpected showers and sun protection are must-haves. Don't forget to pack your camera to capture the picturesque landscapes.

Health and Safety:
Always drink bottled water and avoid street food if your stomach is sensitive. Carry a good mosquito repellent and first aid kit. It's always safe to have travel insurance for any last-minute health or travel mishap contingency.

Local Etiquette and Respect:
Respect the local traditions and customs. People here are very hospitable, so treat them graciously. Dress modestly while entering religious places. Also, ask for permission before taking photographs of locals.