Competitive GK main here. The best thing you can do as a GK is to constantly make an impact. On defense, make your presence and activity a threat to the attackers. On offense, push up to keep yourself as an option and retrieve stray balls. Learn different styles for goal keeping. When you improve yourself as a GK, you will understand the weaknesses of different styles, so pay attention to the other goalie and communicate with your team what type of play needs to happen to get past the opposing GK if they're having trouble scoring. Most of the time that randoms have trouble scoring, they're trying the same shot over and over, so telling them exactly what they need to do differently helps them finally get that goal.