You need to start watching soccer on a regular basis. There might not be too many games being played every day, but you need to set a time for yourself during the weekends. All the soccer action takes place on the weekends and almost everyone is free during these two days. Give some time to the game and start following interesting fixtures which others are anticipating eagerly.
Pick a team. This is absolutely necessary. Once you pick a team, only then you can tell others about something. Follow that team to the core. Understand their history and what they have won. Understand how they managed to win titles in the past and how can they win them in the future.
Start learning all the rules of the sport. This is extremely important. People who frequently label themselves as good soccer fans might not even know too much about the sport. Learning the rules should be a priority. This is because, once you are following soccer while the season progresses, you need to know which decision was taken correctly and which was wrong. You can then argue about each and every decision which was taken by the referee during the game.
Select one player from your team as your favourite player. Tell the world how you like that one player and why you like him. Explain the reasons and buy yourself a few posters and a jersey so that others know that this one player is the reason why you support the club.
Learn the tactics of the game. Tell others about the poor decisions taken by a coach during a particular game. This will explain how you know a lot about the sport. Others will take you as an authentic source and they will ask you questions regarding different decisions taken during the game.