To avoid these problems occurring, you need to adopt assertive, not aggressive, behaviour. Assertive behaviour means looking for win-win outcomes in communication in which everyone ends up feeling good about things. It does NOT mean getting everyone else to behave in the way you would like them to behave - this is aggressive behaviour. It does NOT mean allowing other people to let you do all the work and have all the worry - this is passive behaviour.
Take a moment to consider the following chart. It should be noted that aggressive behaviour can often be disguised be apparent politeness. In other words, just because someone is speaking softly and smiling, does not mean they are not using aggressive tactics.