Let's get started. I figure the first post in the thread should cover some of the specifics about eating out in Florence - when, where, those sorts of things. If I pick up any other common tactical questions in the forum, I'll add them here, or ask away in the thread.

When and Where to Eat
Breakfast: Throughout the morning hours.

In Florence, and most of Italy, breakfast is a light snack and not a full meal. Coffee taken at the bar, standing at the counter, along with a small pastry, bread, yogurt or cereal is common.

You generally will not find breakfast served at restaurants, and I'd caution that if you do, the place is likely a tourist trap. Hotels do often serve breakfast, anything from what we'd call a Continental breakfast in the US (coffee, juice, carbs and cold items) to an American breakfast with hot items as well. If you are looking for breakfast, the words to look out for are Colazione or Prima Colazione. Sometimes Colazione Americana is used to indicate American Breakfast, although it'll usually be in English as well since the target market is not Italians.

Lunch: Generally from 12 to 3pm.

While I'll try to not generally editorialize the advice and factual content in this post, I'm going to make an exception and just mention that lunch is consistently my favorite meal of the day in Florence. I'd encourage a light breakfast and an easy dinner if it means a great lunch.

Most restaurants in the city will run splits, meaning they are open for lunch, closed in the middle of the day, and then open again for dinner (if they serve dinner). As a general matter, if a restaurant is open all day, you want to take a hard look at whether it's a tourist trap because that is one of the signs. There are some exceptions, which I'll mention in my recommendations, of great Florentine restaurants that happen to stay open all day.

As with dinner, make reservations if possible. For the places that don't take any, your best bet is to show up a little before opening, or trying back later on in the last hour of service, unless it happens to not be busy in between.

The Italian word for lunch is "Pranzo."

Dinner: Generally from 7-10pm.

The lunch advice is applicable here as well. I'll add that while fewer restaurants take lunch reservations, most do take dinner reservations and I highly recommend making them. Italians themselves might make plans the week of, so reserving 1-2 weeks out is generally fine, except for well known restaurants with long waits. For those, you'll need to research individually, as I'm talking here about more casual restaurants, and not the high end special occasion variety.

One tip I can offer is that Italians tend to eat later, closer to 8pm. If you're working on getting to a place that has more local traffic, that 7pm reservation would be your best bet. You may, on occasion, be told that they are booked up with later reservations and you might be asked to give the table back by a certain time. This is not rude, they are trying to fit you in. And the ask is usually to have it back for a later reservation (as in, you get the table at 7, but we need it back by 9) as to most Italians a dinner out is a longer affair. Generally speaking, though, the table is yours for the night.

The Italian word for dinner is "Cena."

Meal Structure
A Florentine menu, similar to most of Italy, will have appetizers (Antipasti), first courses (Primi), second courses (Secondi) and dessert (Dolci).

Traditional Florentine antipasti include crostini (toasted bread), the most traditional being with a chicken liver pate on top, Ribollita (vegetable soup thickened with bread), and then some of the more familiar like various cuts of salumi with bread (sometimes ordered by the hectogram, or etto, which is 100g).

Primi are generally pastas, as the first course is traditionally a pasta course.

Secondi more commonly include meats and fish.

Dessert could be anything - fruit, cakes, pastries. I should add that fruit in general is very common after a meal, and that becomes especially true with the older generations. As my father explains it, certain fruits were something they only got on special occasions - in his hometown, oranges and bananas were rare. The idea that you can get any kind of fruit any time of year is a more recent thing, so for some of the older generation, the fact that they can have a fruit salad with things that they only used to see on Christmas is a novelty that hasn't worn off. Oh, and also it's better for you, especially if you just ate 3 courses!

You do not have to order one of each course. It's not expected that you will or will not, and certainly not rude. My "usual" is a shared antipasto (or multiple antipasti) for the table, and then either a primo or secondo, depending on my mood. Or sometimes we each get primi and share a secondo. Dessert if something sounds great or we have room for it (rare).

With many pasta dishes, you can often order a half portion (mezza porzione, or mezzo piatto) - even though it is rarely listed on menus. You can always ask. Generally, for simpler pasta dishes, you can get half, for more complex preparations or things like stuffed pastas, the restaurant will decline. But it is absolutely not rude to ask if you can do half an order of pasta.

Coffee is common after the meal or after dessert. The common wisdom is not to order coffee-and-milk type things like cappuccino after breakfast time. It may seem odd if you do. However, I'm not going to get mad at you for doing it, and the restaurant will probably make it for you anyway. So do what you like there.

What to Look For / What to Avoid

The common wisdom in Italy is to look for menus that aren't too long, preferably a menu that appears to be in-season, and not written in 7 different languages or have pictures. In Florence, that is all mostly true, although given the reality that the historic center is a tourist destination, you will find translated menus. Generally speaking, most of my favorite places have hand written menus - that tends to be a good sign. I mentioned before about the better places generally running split schedules, but if the signs here look good, the fact that they're open all day should not veto the place.

I hate to shift to the negative, but I think I'm better at illustrating what to avoid as a means to finding good food in Florence -

If the menu has pictures, or if there is someone outside the restaurant trying to get people in, that's not a good sign. These also tend to be majority of the the places open all day.

A big thing to avoid is a menu that is lengthy or looks too familiar. By that, I mean to indicate that Italian food is very regional, and you tend not to find in Florence a lot of what we in the US know as Italian or Italian-American food. In particular, Spaghetti and Meatballs or Chicken Parmesan on a menu are total showstoppers, as those dishes don't actually exist in Italian cooking. Meatballs exist (polpette), but they're not served on pasta, they are a separate course and they usually don't look like they do in the US. Similarly, stick to places that represent one city region - preferably Florence/Tuscany since that's where you are, but Florence has some pretty good restaurants that represent other regions as well. This is probably the place to mention pizza as well - if a place serves 50 other dishes and pizza as well, you don't want the pizza. Pizza is served in places that more or less focus on that, and they should have a wood (not gas) oven - "forno a legna" is what you're looking for.

Snack bars are also really common, and quality varies wildly. Particularly near tourist attractions, you might see them (sometimes even called Snack Bar, in English) with a glass case full of things - sandwiches, pizzas, pastries, gelato, etc. You're rolling the dice here and I'd say buy here only in a pinch, as it's more likely that the food was mass produced than made in the back that morning. If you want a sandwich, there are lots of little sandwich (panino) shops throughout the historic center. If you want a pizza, there is actually reputable pizza in Florence. If you want gelato, there are many places that do it justice. A snack bar is about convenience. They are, however, a good place to drink a coffee at the counter, as long as you see a machine back there. Remember that the price is different if you sit down, and the local custom is to drink it standing up at the counter.

Location is also important, but not in the way that you might think. As a broad generalization, if it's in Piazza della Repubblica or Piazza del Duomo, don't eat there. The large restaurants in the expensive real estate are usually disappointing.

Finally, the one place that breaks all of my "avoid" rules that is actually great and I will mention by name in this section. The Mercato Centrale has a second floor (Primo Piano, as they number floors differently than we do in the US) that is open from morning to midnight, has nearly anything you could want to eat or drink, sometimes has pictures on the menu and is in prime real estate. I highly recommend it when you want to eat in off hours, don't know where to go, or might otherwise stop in a place you know you should avoid for lack of known better options. This is your fallback plan at the least, and a destination in its own right. It is a collection of food stalls run by well known local purveyors and is great.

I'm going to continue to add to this section. There's a lot of great food in the historic center of Florence, but even more bad food to steer around.

Typical Florentine Cuisine

I'm sure I'm going to miss a lot here. I'll keep adding as I think of things.

Traditional Florentine food is very meat-centric, as well as heavy on beans and lard/oil. Compared to the south, there is less tomato involved. Compared to the north, there is far less polenta and chickpea. Pasta is very common, and Florentines like Ragu Bolognese a lot more than they'd be willing to admit.

Bistecca Fiorentina is probably the best known dish, which is a porterhouse cut from Chianina cattle. It is grilled and traditionally rare to med-rare ("al sangue"). Menus often list it priced by kilo or etto (hectogram, meaning 100g), and when you order you can indicate roughly how large you're looking for, but it won't be exact as the steaks will have already been cut - either in house or by the butcher - that morning. However, this is usually a dish for at least two, or for the whole table, as the cuts generally start at 1kg.

Ribollita is essentially a vegetable soup thickened with bread and one of my favorite things to eat.

Tripe (trippa) and lampredotto (the 4th stomach of the cow, no idea what the English translation is) are traditional street food, usually served in a sandwich with red (tomato) and green (herb) sauces.

White beans are everywhere, especially as a side. It's hard to go wrong with white beans, olive oil and some herbs.

Porchetta is a rolled pork belly roasted slowly and sliced. Usually on a sandwich, or served with the skin crisped up on a plate.

A note about Florentine bread: Traditionally, it is not salted. Actually, this is common throughout Tuscany. I have no idea if it's true, but the story goes that Pisa once cut off Florence's salt supply (as it would arrive at the port of Pisa) in an attempt to win a war. In any case, this is one tradition that I don't enjoy. They have better bread in Pisa.

I know I'm missing a ton, I will continue to edit this thread.