Here is how we pick where we are going to eat.
First we go through the guidebook and list the places that interest us. We have all the adults and children old enough to have an opinion make their lists. We compile them up and see if there is anything that is on anyone's "must do" list (Marrakesh is always on my husbands), then which ones are popular choices. If we are in a budget mood, we note the expense involved with each restaurant.
Then we figure out where we "think" we will be when lunch or dinner rolls around (or breakfast, particularly for a character breakfast). We usually do counter service for lunch, and sit down with PSs for dinner, but a lot of people like to do their sit down meal at lunch when its cheaper. We match the top hits on our list with where we think we are going to be - if budgeting, we take into account how expensive the restaurant is (or when traveling with small children, how child appropriate). We won't hit every restaurant on the list in a trip. Sometimes, there is no restuarant for where we are going to be. For instance, sit down in the MK has never appealed to us (sorry all you castle fans, more room for you, I guess), so we leave the park and do a nearby (or even far away) hotel, Downtown Disney, or park hop over to Epcot, where we like a lot of the restaurants.
Our traditional path takes us to Epcot or the hotels for our evening meal, Epcot is open later than the rest of the parks, which makes it a nice evening meal stop. And the restuarants are one of the big draws for World Showcase.
So, lets say you decide you want a Character Meal, and doing some reading, you decide Breakfastasourus at AK is your deal. Get a PS for that one the same morning you'll do AK.
And you really enjoy German food, so you get a reservation for the Biergarten in Germany the night you know you'll be in Epcot.
You really want to check out the Grand Floridian, even though you can't afford to stay there, so you book Narcoosee's the evening of your MK day.
etc.
Check out the menus at
www.wdwig.com for some idea on what is served at each restaurant and prices.
You probably won't want to do PSs for every meal - it involves a lot of planning and sticking to a schedule - (some people do, some people make none at all and fly by the seat of their pants, most of us make a few, eat at a non-PS place for a few meals, and wing a few sit down PS places as well).
Keep in mind as well that you don't NEED to keep your PS (except for credit card events like holidays or Cindy's breakfast, where you will need to keep your reservation or cancel in advance), its nice if you can call and cancel - but since they aren't reservations, your table isn't being held if you aren't there. And that calling the day of if you change your mind (hey, there is a restuarant in the Living Seas and it sounds cool!) often works, so there is a little flexibility - although I believe you are better off getting some PSs before you leave.
