While communicating with other people, we might say a lot or hear a lot. Despite a large amount of available information during communication, a lot is still left out leaving gaps in the picture.
We often fill these gaps with assumptions. This might rarely be a problem with people close to us that we spend a lot of time with but what about new people, groups, topics, projects, tasks etc. ? In these cases our assumptions might be off more often leading to misunderstandings and wasted time.
The solution for problems in communication is, who could've guessed it, communication :D .
To avoid other people misunderstanding us, we need to continually practice and get better at our communication and better at ways of getting our point across as precisely and concisely as possible.
To avoid making wrong assumptions we have to continually practice careful listening, ponder about what is being said and while doing so ask questions or reiterate if in doubt or lacking understanding.