Starting a team takes a commitment of time and energy, to develop players, build a website, form rules and guidelines, practice strategies and make a cohesive gaming unit. DO NOT let it get to your head that you are a team leader. Many teams have been destroyed when a leader thinks that because they are in charge of a good team, that they are superior. Ego will ruin a solid team quicker than anything. As a team leader, you must remember 2 important things. You are there as team leader to support your people, they are not there to be your support crew. The team is always "our" team, not "MY" team. If you form a team, and people see that they are part of a team, and not an asterik to your gaming, they will stay around. The other important thing is to have a viable chain-of-command, with a balance of power, and a backup plan if the team leader is not able to be around for an extended time. "As team leader, I will be out on a vacation for the next 3 weeks, so this guy is in charge while I am gone." If you have a solid team, they will be around when you get back, whether it is 3 weeks or 3 months. the team might not function as smoothly, and there might be some issues to resolve, but the team will still be intact.
Start a solid team, and build a good foundation for the team, and it will be around for years. A personal story: I joined a team, and then me and another player quit to form our own team. He was in charge, I was #2. After a year or so, he left to play different types of games, and I became the team leader. The team has now been around since March of 2001, 5 years and counting. The average lifespan of a team in a FPS game is around 3 months.