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.
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.
Take some tissue papers with you. This will help you to clean your seat or your hands during the journey.