Don't walk and text. This is a big one. There's no ban yet, as there is on texting and driving, but there should be. If you have your phone out — even to track where you are on a map — you're walking too slow. And definitely don't "multitask" on the subway stairs. There's a whole crowd glaring at your backside, wishing you would briskly get to street level, then find an out-of-the-way spot to talk, text or tweet.