Predictions about future based on natal chart

Recently I've developed more interest in astrology and along with my chart, I'm trying to read the Natal Charts of my family members too. When I was reading the chart of my brother, I told him about different traits of his personality based on different placements, then he said that —I already know myself, what's new you are telling me? If you can you tell me something about my future like my career and that when I??ll get married, how will be my married life then tell me.??

Please advise how can we make predictions about future (career, marriage etc) based on natal charts—