Here are some tips to develop your assertiveness. If you say what you mean and mean what you say you will convey clear messages. You'll have more chance of your needs being met. In our conversations and meetings, seek a win win. In that case no one loses out. You will both exit the conversation or meeting feeling good about what has transpired.
Deciding upon what will you accept and not accept as a healthy starting point. Then think about what you would really like to achieve and aim for that first. As long as it doesn't impact upon the rights of others. You are responsible for your behavior so don't violate the rights of others. If you practice writing a script that can help us do so describe what you find unsatisfying. express how you feel about the situation.
Specify what you would like to happen. State the outcome you foresee if things do or do not work out the way you would like. Finally, remember that assertive people are in control and are accountable for their actions. No one else is accountable. Only you