Before you begin eating anything anywhere it is a good idea to know the difference between various types of  catering establishments.

A kafenion is the simplest form of eatery; at least one that I know doesn't even serve metzes, only drinks. However, most do serve a simple snack (sometimes free with your alcoholic drinks), while others are able to provide a typical Greek salad and tsatsiki with fresh bread. This is most likely where you will find the local men sitting, whiling their time away over a game of backgammon or cards. I say men because local women rarely join their menfolk here. This is not a law, just a custom, and there is no problem, no raised eyebrows when women do arrive. At least, no more interest than when any stranger appears there, man or woman!

A taverna is much more a place for eating, although it is perfectly acceptable to only stay for a drink at lunchtime. Just don't take up a table that is set for meals, ie with a tablecloth, unless you check first that is ok.  Some tavernas are full blown restaurants and serve all types of food but many are grill houses and are not licensed to cook food in the oven. In these you will find all meat is cooked on a spit or barbecue. At night you may find your bread toasted on the spit too. This is because local bread has no additives and only lasts a day, so by the evening it is sometimes tastier if it has been toasted.

A restaurant is exactly what you would expect it to be. A place where you would go more formally for a full meal, usually in the evening although most are open at lunchtime during the holiday season.

A fish restaurant specialises in serving all types of fish but don't expect it to be cheap. Fish is as rare in the Mediterranean as it is in the North Atlantic. Factory ships and overfishing has seen to that and the Greeks have their quotas too.