1.Better eat less from stations and trains. And for sure, the more you keep away from dirty, fly-infested food sold by unhygienic vendors, the better.
2. Do not befriend fellow-travllers to the point of accepting anything, whether snacks or else, from them. Be vigilant and be on your guard.
3. Talk low on mobile phones and with others; be respectful.
4....
more... Do not litter anywhere. Pick up any garbage yourself and toss it to a bin.
5. Close the bathroom door if you find it open.
6. Don't stretch out your legs to the alley blocking other passengers.
7. Be courteous, dignified and friendly ( but matter-to-fact ) with other passengers.
8. Do not be passive to any criminal activity / nuisance on the train, regardless of who is the perpetrator.