When you’re lucky the people who sell the traintickets speak English. The best way to arrange a trainticket is with a note from the hostel. Every hostel will write a note for you. It’s way easier with this note. Check before you go if there are traintickets en write the number of the train on the note aswell.
Train from Xian to Chengdu
With three other travelers I booked a trainticket for a 16 hour trainride from Xian to Chengdu. I always prefer the hardsleeper. I’m not that tall and the beds are good. We bought some food and beers for in the train. This trip I slept 8 hours so I was fit enough to sightsee Chengdu the next day see the panda’s and eat hotpot!