I would definitely try and be someone your team's members could talk to. Our leader this year definitely was a very positive influence on me, as well as the rest of my team. Also, don't take everything seriously, laugh a little (or a lot) and definitely embrace your mistakes and errors.
Another thing you should try to do is involve new members. When I joined my team back in 2014 I had no idea what I had gotten my self into. All these people shouting for zipties and ducktape?! Whenever I wasn't doing anything they involved me. I did that with the freshies this year too. At kickoff they were clueless about what FIRST even was, and now one is a human player and the other is one of the higher mechanical people!
Do these two things, and you'll do just fine, I am sure
