Honestly, it's really hard (in my opinion, but maybe I've just had the luck to have really bad experiences) to get high school students to really get into the role of being leaders. It just doesn't seem to be in them to be able to turn around and say "No, this simply won't work" to friends, or to really get on someone's case for not doing something. In the few years I've been FIRST, I saw maybe 2 natural leaders in the team I was on.
The model that CHS Robotics (2473) uses is senior-junior mentorship. We try to place the veteran team members in positions where they have to train the rookies in the skills necessary for robotics, engineering, and leadership. The mentors are there to step in when necessary and to provide guidance and mentorship for the veteran team members. The problem is that many of the veteran members are simply not mature enough to be leaders or teachers.
As for how I personally lead. I lead by example. As team captain, I spent the most time in the lab, of the entire team. As a leader, you need to do 200% of what you expect your subordinates to do. I also lead by setting a very clear objective for the team. I always had a schedule posted on the wall, where everyone who wanted to look could look at it. Keeping in touch with your subgroups is also important - everyone needs everyone else to be successful. I did this using meetings, but dinner, walking around and chatting, and a systems engineering department (if you're lucky to have those resources) work just as well. Another key thing about my leadership style is discipline, and you'll hear this from many leadership trainers. As a leader, you need to hit the team fast, hit them hard, and hit them often with discipline as soon as you become their leader. It's so much easier to slack off with discipline that to ramp up discipline partway through.
Leadership is essentially the same set of skills, no matter what industry you're in. I would suggest looking at the NOLS leadership course - while it's designed for outdoor leadership, many of the situations are similar, and I feel the way they put the material is quite effective.
http://www.nols.edu/about/leadership...p_skills.shtml
Edit: To add on, one of the biggest things to being a good leader is having a vision of what YOU want your team to be and do, and convincing the people you lead to share that vision. Thanks to Mr. Charles Williams for that advice. It's what has kept me going.