Your host may offer it to you. Don't put your thumb between your first two fingers. It is a very very rude gesture. Women should be accompanied by a man in restaurants and in hotels. This custom of relying on a man makes the man look good in public.
Business people dress conservatively with good shoes.
Men should not take off their jackets without asking. Dress casually for dinner in someone's home. In cold weather, wear a hat or old ladies will lecture you on your foolishness. Men should bare their heads. Do not whistle inside or you will whistle away your money.