After sitting down, place your napkin on your lap and eat with your knife in the right hand, the fork in the left. Be warned that if fish is on the menu, it will most likely be served whole. As you finish eating you will be offered more food, but turn it down. If you truly are finished eating, leave a small amount of food on your plate, if you want more food, finish all your food and accept your host's second attempt to give you more food.
Many sit down restaurants include a service charge, but if not, you should tip about 10% of the bill. Small tips for bar tenders are also appreciated, but not necessary.
Drinks
Between Italian and Turkish influence, the Croatians love their coffee, which can be found as a dark and strong Turkish-styled coffee or in a lighter version. The Croatians also enjoy their mineral water. Of course tea, juices, soft drinks, and milk are also widely available.
There's a growing wine industry in Croatia, however most wines haven't quite hit international standards. These wines tend to be very sweet so are sometimes mixed with water when poured. A more unique alcoholic drink found in Croatia is rakija, which is plum brandy. There are also other brandies made from grapes and herbs similar to rakija, a regional specialty. Popular international beers, wines, and hard liquors are also widely available.
Generally speaking, the tap water is safe to drink in Croatia, but check with locals for any particular regional differences. Also, many people may have troubles adjusting to the local tap water, as it will most certainly be different from what your system is used to.