I'm not going to say I'm a total expert, but after a few months experience (if they ask, 2 years) as a waitress I was seeing the same 10 tables over and over again. The good part about this is, is that it was easy to know what to expect, regarding the group behavior and some times, the tips.
So here are the 10 most common ones, their best, and their worst.
10. College students: A group of early twenty somethings, usually around 6 people, and they NEVER have a reservation.
Their best: Usually friendly, patient and relaxed.
Their worst: They stay until you start moping the floor around them, if you let them.
Their orders: Something to share, chips, and the cheapest alcoholic drink available.
9. The lonely gourmand: They don't see anything wrong with dinning alone, and why should they? They are here for the food, and sometimes the wine. Sometimes they bring a book or laptop, to have something to do while they wait.
Their best: They are passionate about food and are among the few ones that really "get it".
Their worst: They feel really entitled to especial treatment, and if they are into social media, even to free stuff.
Their order: They might ask for the chef's special, the best seller of the place or the most difficult dish to make in the menu.
8. Wall Street wannabees: A group of middle aged business men, fans of the three-martini lunch, that gather to do some small talk and maybe close a deal.
Their best: They make reservations, show on time, and spend a lot of money.
Their worst: They leave unsurprisingly ungenerous tips, are condescending, and sometimes blatantly arrogant.
Their order: Steaks and lobster. They ask for the wine list and order an expensive red or whiskey.
7. Tourists: They are the only ones not taking pictures only of food or themselves but also of everything else. They expect that you recommend them the best local attractions (even if it's your second week in the country), and are eager to try some local dish (even if the place is an Italian restaurant).
Their best: They are friendly and sometimes reward you with a good review.
Their worst: They are a tip roller-coaster (Americans and Scandinavians tend to tip on the generous side, Mediterraneans on the nonexistent side).
Their order: The "local favorite" or, in an opposite note, their safe choice (something well-done with no raw vegetables or ingredients that might ruin their trip if it's slightly unwashed).
6. Office lunch pack: They are arrive hungry at 12:30 pm, and their only need is to leave the place full at 1:00 pm. Usually they don't book ahead, but call just before going to see if you have a table for 12 ready.
Their best: They order the easiest and fastest stuff from the menu. Sometimes even pre-order on the phone.
Their worst: They have ZERO patience. Many see themselves as Wall Street wannabees and behave as such.
Their order: Soup, sandwich and Light Coke.
5. The first daters: Awkwardly overdressed, they use their choice of food and their treatment of the restaurant staff as a way to make an statement about who they are.
Their best: They normally avoid making odd requests of being particularly annoying.
Their worst: With them, you are on thin ice, and if you make a mistake, it's the end of the world and they can turn into bitter jerks.
Their order: Prosecco, a main that is clean easy to eat (no bolognese near his new white shirt) and chocolate cake for dessert.
4. Girls night out: They look like they are going to a party, but then stay in the restaurant. Too shy to say "let's go to a bar", but not to chug a bottle of wine with dessert (each).
Their best: They are hilarious by the time of dessert and if they leave happy, they tip nicely.
Their worst: They make very irritating requests, and if the waiter is a cute guy, they will annoy him to death.
Their order: Salads or appetizers instead of mains, and then dessert. And a LOT of white wine, usually something fruity and inexpensive.
3. The ones with the toddler: I understand that moms and dads need to have date night too, but the kid? They didn't have anyone to leave it with, and though no one would care if they bring him/her along.
Their best: They feel guilty all the time so, if you play nice, expect to be rewarded.
Their worst: If they kid is well behaved, they are fine, but sometimes their child is just so annoying that no matter how good their tip is, it won't compensate they rest of the unhappy tables.
Their order: No stater, just main, and something for the baby to throw in the floor. Plus apple juice.
2. The fighting couple: If you think you are on thin ice with the first daters, you'll envy the stability of an ice road trucker with this ones. He's frustrated and she is crying. Then they talk in whispers but it's too late. The best thing you can do is to avoid eye contact and don't approach the table, just wait to be called.
Their best: They eat fast and leave early.
Their worst: They make everyone around them feel awkward and can be very very rude to the staff.
Their order: It doesn't matter, they'll say it was horrible.
1. The regulars: They come often and have tried all the menu. Maybe friends with the owner or the chef, maybe they live nearby or their office is in the same building. Sometimes they even call you by name.
Their best: They tend to be on the friendly side and leave a decent tip.
Their worst: They hate change (that's why they always go to the same restaurant!) so if their favorite table is taken or the dish they like is no longer available they will get visibly upset. At you. Also, they will feel they have the right to make odd requests. If you are the type of person that doesn't like small talk, you'll hate them.
Their order: The set lunch option during the day, their favorite dish during the night. One time they might try other stuff, but they always go back to the same choice.