The waiter will bring you beers without being asked until you say "zaplatim" – meaning that you're ready to pay. Don't share a beer, don't finish someone else's beer and don't pour beer from one glass into another.
In the Czech Republic, toasting and drinking are taken very seriously. The common toast is : Na zdraví! – To your health! You should look into the eyes of the person you are toasting and not break eye contact until the moment you put your glass down.
Beer & drinking etiquette in the Czech Republic:
Don't go to the bar to order. Sit and you will be served.
Don't pour the dregs of an old beer into a fresh one. This dishonours the beer. Beer usually accompanies meals. Drinks will usually come out onto the table, along with snacks, during business meeting, at virtually any time of day, including first thing in the morning.
Don't get upset if someone brings you a beer you haven't ordered. The more you drink, the more you will be offered to drink. While the waiters will usually ask if you want another for the first couple of rounds, as soon as it looks like you're settling in, they may start dumping beers in front of you every time you're getting a bit low. Either say "Zaplatim" or put your beer mat on top of your beer to show that you are done.