Bargaining and tipping
Since most stores have set prices, bargaining is not a common part of life for tourists. It is worthwhile to bargain for a lower price while renting a car or a room, especially during off-peak times. However, it's better to avoid being pushy; for instance, ask if they have a cheaper accommodation rather than insisting on a lower rate.
Although most taxi drivers expect tips from visitors, and the majority of service personnel are paid extremely poorly, tipping is not required anywhere. The service charge is already included in restaurant bills; if you want to tip, rounding it up usually suffices.
Smoking should also be included. Greeks are the biggest smokers in Europe, and despite the fact that it is against the law to smoke inside of bars, restaurants, or other public places, this rule is largely ignored in daily life. Effective smoke-free spaces are quite uncommon.