An all purpose word of greeting is Merhaba. It's easy to remember, easy to pronounce (as spelled) and can be used all day long.
An absolutely magical expression is: kolay gelsin. It translates as "Don't work too hard" or "take it easy", and is used as a form to say good bye and can also be used as a greeting. A foreigner who knows that expression has conquered the heart of the Turkish person so addressed!
In the street, you may shake hands, if the hand is extended toward you. Do not shake hands, hug or kiss a person of the opposite sex in public.
When you're invited to a Turkish home, you should bring sweets, chocolates or flowers; do not bring a bottle of alcohol. Take your shoes off before entering the home, even if your hosts say that there is no need for it. Turkish families possess a wide range of slippers sitting by the door, which are offered to guests after they have taken off their shoes. Don't show the soles of your feet or shoes toward anyone. Do not point your finger at another person and don't blow your nose in public.