Customs and habits of usa

Picking your nose This activity is considered childish by Americans and makes you appear uncouth. Do not do it in view of others.
Bathing  Customs surrounding bathing vary around the world. Americans typically bathe once a day in hot water and shower directly after strenuous exercise. They also use underarm deodorant: if you have not brought any with you it is recommended you buy some as hot, humid summer weather or stressful business meetings are no excuse if people smell you before they see you. Americans will back away from and not befriend or do business with people who smell bad.
Shaving American women typically shave their armpits and legs. This practice is not universal, but some people will have a strong reaction to armpit or leg hair on a woman. For men, shaving is often a personal choice and how one wears his facial hair is often his business, thought generally keeping beards and mustaches trimmed and neat is preferred.
Hand Washing It is 'good hygiene' to wash one's hands after using the toilet or if you one is about to handle food (many American families wash their hands before gathering around the dinner table, for example; this is what is meant by "washing up.") In many restaurants you may notice a sign demanding that employees wash hands before returning to work: it is the law in many places, in order to prevent disease from spreading. Foreign visitors would not at all be considered exempt from the practice of hand washing.
Flatulence: Bathroom humor is a staple of comedy in America, but it is also a taboo as well: Lifting your behind up and breaking wind in front of somebody is not a good idea, and would certainly be the end of any business or personal relationship with a woman. Burping loudly is not a compliment to the chef in the U.S. It is frowned upon and is actually very poor manners.
Public Transportation Courtesy:
Boarding: It is typical policy for most buses to board from the front door, unless if policy says it is allowed to board other entrances with proof of payment. Passengers should never evade paying their fare to ride public buses by entering through the rear door and board the bus until all passengers, including elderly passengers exit first. On subway cars, is is basic courtesy for boarding passengers to line-up on the sides of subway train doors and permit exiting passengers to leave directly out of the doors.
Exiting: Passengers on buses should get the bus operator's attention by pulling on the cord near the window or a designated button located on poles on the vehicle. The "bell" should be rung at least one half of a block to permit the bus driver to make a smooth stop at the designated bus stop. Late activation of the "bell" system may result in the stop being intentionally skipped, force the vehicle to stop immediately, stop several feet away from the designated stop, or cause passengers to be upset. On all transit vehicles, passengers should be prepared to exit the vehicle by moving towards the exit doors, and should never be seated when the vehicle arrives at the stop.