Everyday Etiquette for Public-Place Encounters

On a rainy day, when everyone is carrying an umbrella, how should I keep from bumping mine into other people? And what are the proper times to open and close my umbrella?
The tall ones need to take charge here. If two people are sharing an umbrella, the taller person should hold it. When two people carrying umbrellas are walking toward each other, the taller person should always raise his umbrella to allow the shorter person safe passage.
 
The rule for opening an umbrella is simple: Keep it shut until you are fully outside and clear of the door. Before entering a public building, Purdy says, "shake off your umbrella outside. If you get a little bit wet, that's what happens when it rains. A few raindrops on your head are preferable to creating a wet mess in someone's place of business."
 
The same goes for public transportation. When boarding a bus in the rain, always turn your back to the door, shut your umbrella, then make your entrance. "Otherwise I get sprayed, and the water on the floor makes things slippery," says Aretha Bull, a bus driver for the Los Angeles Metropolitan Transit Authority. Finally, never place your wet umbrella on an open seat or you'll put a damper on someone else's day.
 
 I'm at a crowded airport and I see a pregnant woman or an elderly person looking for a seat near the gate. I don't have one to give her, but should I ask someone else to give up his seat?
Give it a minute. The person will probably speak up for herself. If she does ask and her request is declined (or if she's clearly uncomfortable but appears too meek to ask), then it's fine to step in, says Cohen.
 
"If you ask one person and he says no, chances are someone else is going to offer," Shade adds. There's no need to keep asking on down the line.
 
 Is it OK to read over a person's shoulder?
The experts are split on this one. Bull flatly says that it's impolite: "People have to have their own space." Purdy agrees that leaning into someone's personal space is inappropriate but says, "If you're at very close quarters, how can you help it? If someone's newspaper is over your head and you're reading the back page, that's polite. Asking them to turn the page isn't."