Things to do, not do, or just keep in mind when you visit India and Bangladesh (well, mostly India):
1. There's a big difference between 1rst class and 2nd class train travel in terms of accommodations, cleanliness, food, comfort, etc. Always travel 1rst class. (Also, read what Mark Twain wrote about Indian trains in his "Following the Equator". Is it possible they are still using the same trains?)
2. Take Cipro every day!!
3. If you take Cipro every day, then you can eat a little more adventurously, So eat the samosas made by the vendor just outside the Sri Ramakrishnan monastery in Calcutta. They're wonderful! You can also safely drink the chai on the trains.
4. Visit Varanasi (Benares) if you want to understand Hinduism. And by all means watch the Brahmin priests offer fire to "Mother Ganga" on the banks of the Ganges.
5. But if you do go to Varanasi, be prepared for a strong shock to your sensibilities. Some of it requires a fairly strong stomach.
6. Speaking of strong stomachs, eat at Karim's in Delhi. It's close to the south gate of the Jama Masjid mosque. Try the grilled goat. It's delicious!
7. You can do one or two overnights on India trains, if you go 1rst class and don't try to do them on consecutive nights, but don't try to do four. Also, next time I'd like to try a long 1rst class day trip.
8. Pace yourself. India is huge and you can't see it all in one visit. Decide what you want to see. Also, don't do too much in any single day.
9. The Taj Mahal is gorgeous but the Red Fort is (to me, anyway) more interesting.
10. If I had it to do again, I would spend more time going to see the sites associated with the British rule of India (Lucknow, Simla, and more of Calcutta).
11. I would also like to go to south India and find out more about Indian Christianity.
12. Next time I'll plan better and actually see some of Mumbai.
13. Skip the changing of the guard at Walla Bagh. It's hot and boring (although it tells you a lot about the relationship between Pakistan and India).
14. Speaking of hot, DO NOT travel in July or August. Try to go during late fall or winter.
15. Kingfisher beer is great.
16. Jet Airways is a terrific airline.
17. Hire a local guide. There are things they know and can do for you that you cannot know about or do on your own.
18. Eat at the Crystal restaurant in Amritsar. It was by far the best restaurant we visited. Also, order their Murg Frontier.
19. Make a list of all the odd signs you see, e.g., Guru Nanak Honda, Krishna Used Vehicle Parts, etc.
20. Make a list every day of the unusual things you see, e.g., women in saris riding motorcycles, whole families sharing rickshaws, etc.
21. Finally, and most importantly, visit India. I suspect that most western visitors (esp. from the US) think about turning around and going home for the first 2 or 3 days. But if you let go of your expectations and preconceptions and don't expect India to be just like the US, it becomes fascinating.