Before you start the journey, always check the route and make sure its safe to travel from that route specially if you are planning to travel during night.
In case your family members have not got adjacent seats during automatic seat assignment then make a humble request to other travellers and try for seat exchange so that all of you can sit together.
When your destination is about to arrive, just be ready with your bags and count all the items. Most of the people do this mistake and they often miss their belongings in the bus.