Greece is a safe country to visit. But you also should take care of your belongings. lock rooms and cars securely, and to keep your valuables hidden, especially in cities.
If you do need to go to the police, always try to do so through the Tourist Police (t171), who should speak English and are used to dealing with visitors. You are required to carry suitable ID on you at all times – either a passport or a driving licence.
Drug offences are treated as major crimes, particularly since there’s a mushrooming local addiction problem. The maximum penalty for “causing the use of drugs by someone under 18″, for example, is life imprisonment and an astronomical fine. Foreigners caught in possession of even small amounts of marijuana get long jail sentences if there’s evidence that they’ve been supplying the drug to others.