I really love the long distance journey by train, because, it gives ample opportunity to sleep, without any tension. You can order your foods, and the guys from pantry will come and wake you up to give the food. And everything comes in time, from morning tea/coffee, breakfast, lunch, evening snacks / tea / coffee , dinner. So you got everything at your place. And the cell phone most of the time is out of network, so not much calls. That helps to sleep nicely.
In India, always book a 2 AC berth, because otherwise, its a pain traveling in other classes, as there will be lot of littering by several small vendors, and there is also possibility of theft and intrusion. These guys do not enter the 2AC or 1st class however, so life is smooth in those compartments. The only exception being, if you have a small kid near you who cries a lot ( Experienced once :), felt like I should get down and go by another train)
I try to book the most comfortable seat in 1st class and make sure to pack a small blanket and a cushion to nap comfortably. I wear comfortable clothes or pack some to change into if it is a very long train journey. I put my handbag or backpack behind my feet and out of sight of possible thiefs, I take a tablet with me in order to read or write or watch a movie or listen to music and I pack some water and food and in case it is warm I pack something to refresh myself, possibly an extra shirt if it is really warm. Have a pleasant journey :)
Long trips are very boring. How do we enjoy it? I usually spend my time reading novels. I downloaded it via cellphone. Reading novels will bring us into the story no. I can spend 5 hours reading the novel. If I'm tired, I can sleep. On the train it is very comfortable to sleep compared to the bus.