Ok, guys. Speaking from what really annoys me...
What NOT to do:

Don't do everything for us, we probably aren't on FIRST if we can't carry the control board or cut a wire

Don't act macho, we don't care how "incredible" you think you are.

Don't stereotype us girls. Most of us robotics girls, aren't the typical flakes (not insulting flakes!)
What to DO:

Be polite.

Offer to help, but don't insist if we refuse.

If you know us well enough (not first time meeting), talk about something we both enjoy.
Hope this helps!
