Ahh. I belive I should have start out by saying welcom to FIRST
I have learned a lot thanks to my mentors. You are going to want to do all calculations such as physics ones, the limits of your electronics (such as how much current it can supply). Often times the simplest solution is the best, especially for a new team. Never take the screws all the way out of the jaguars.
Try your hardest to finish most of your robot early enough to allow the programmers time to work on the bot too. Always always always use blue lock-tight on set screws, or anything else that has any chance of working its way lose. Check bolts often.
Make sure your drive train is capable of what it needs to early on in the season.
On my teams 09 robot the frame was rigid but the impacts it had to endure were so great by the state competition it was not the same shape it stated out as.
Make sure if you uses a smaller motor that it can handle anything it might encounter. Basically don't design it to stall or be anywhere close to its limits.
Try to prototype somethings if you can before actually making them a part of your robot.
That's all I can think of at the moment. I would also try to find another team by you that could maybe show you some of what they have done. Good Luck and we'll see you at the competitions.