I can only tell you how I order, and that is British English. If you'd like to call the waiter, you do not snap your fingers or shout, "Waiter!", or "Excuse me!" You raise your hand looking at a waiter, and he or she will acknowledge you and come to your table. Once the waiter is at your table, he or she will probably bring you the menu and ask you if you'd like something to drink. When they are back with your drink, they will ask you if you are ready to order and you can say something like, "Yes, please" followed by "I would like the vegetarian pasta please," or "I'll have the vegetarian pasta please." Bon appetite! :)

In U.S. restaurants, you don't really need to. You enter the restaurant and there is a counter. A host, sometimes called a "maitre d'", asks you if you have a reservation, and, if not, how many people are in your party. If it is busy, you wait near the desk until they call your name, or they may say "Come right in." Someone guides you to a table and seats you. That person might or might not be your waiter. In any case, at this point, they know where you are and are keeping track of you. A waiter will come and will take care of everything... asking questions as needed. They know the reason you are at a restaurant is to order food and eat! When they bring you the menu, you can order using any form of words that makes sense. You could even just point to what you want!

If your level of English is good enough to read the menu, then you can ask for a menu. You can say: "I'm (we're) ready to order now." If the menu has a numbered list then you could ask for menu item number 1, 2, 3 or whatever. If you're not sure or if it's the first time in that restaurant then you can ask the waiter or waitress: "What is the special today?" or "What do you recommend from the menu?" Then you can respond: "Thank you, we'll have the chicken special, the fish, and so forth."

Say "Excuse me, please" to get a waiter's attention. Then say "Could I/we please order now?". Then you can say "Could I have/get/order..?" or "I'd like...". Don't forget to say "please". If you want to then order drinks or order another another dish, you could say "Could I have that with...". In more informal settings (e.g. at a café or bar), you can replace "could" with "can".

Are you asking how to get the attention of your waiter/waitress? Or are you asking what to say when they are at your table? If they are waiting for you to order, you can tell them your request in several ways 1. Hi. Can i get a large cheese pizza please? 2. I would like to order the steak. Please add onions and mushrooms on the side. 3. I'll have the salmon, please All are okay. #1 is more informal though, but can be used at a bar or pub If you want to get the waiter's attention, just say "excuse me. I am ready to order"