It pulls into a small station where the platform is full of people wrapped in shawls, walking up and down to keep warm or huddled around a brazier. Then the chai-wallah comes along with his mournful cry and serves cups of tea through the bars of the carriage windows. Sometimes the cups are sun-fired mud and, if you drink too slowly, the soft silty taste of India itself seeps into the brew. Then a dozen arms reach out and the cups make a lovely pop as they hit the wooden sleepers, a noise that champagne manufacturers have been trying to emulate for years but never quite mastered - the sound of an Indian train celebrating its own departure. Also watch out for the start and finish of the school holidays.
Some trains have foreigner quotas, payable in hard currency.
A locking bag with chain to attach it to your berth can discourage sneak thieves. Bottled water is available in much of India. Check the seal is not broken. Sheets and pillow only come with first class, so take what you need for second. Wandering around like a lost sheep guarantees a slaughter.