Going to vaishno devi mandir is very good choice, after reaching jammu tawi please use train for travelling to vaishno devi station dont prefer buses because there are many dangerous turns in the mountain roads.
And may cause vomitting when going for yatra book yatra tickets for vaishno devi otherwise the officials wouldnt allow you to enter the main gate.and always try to start yatra after 3pm cause the climate becomes cool and help you in getting in mandir without any problem and try to not to take too much rest after reaching huge height take some rest which will help you to decrease pain otherwise the place is great cleaniness in the area is good.personal suggestion beware from the horses.