There's nothing inherently complicated about cooking for a large number of people, but it does require a little more time and planning than your average meal. A small investment in scratch pads and research can make the process much easier, and it also helps to have a few friends with large pots.
Consider Your "Production Facility"
Professional chefs have a clear understanding of what can be prepared in their kitchen in any given time frame. When planning a meal for large numbers, consider your own kitchen in the same way. For example, if you're using your oven to cook part of the meal, it won't be available for keeping things warm. Likewise, if your oven can hold only two baking pans, you can't count on warming six pans at a time, unless you're on good terms with the neighbors. Your local rental companies probably have restaurant-sized pots and warming dishes available, and these can be a great convenience.
Consider the Occasion
When planning a large meal, stay focused on the nature of your occasion and guests. You won't want to serve beans and wieners at a wedding reception, and Beef Wellington is not the best choice for a kids' party. Decide whether your guests will be standing and circulating or sitting down to a formal meal, and select dishes accordingly. This will also play a part in deciding whether to make several smaller dishes or a few larger ones. Also, remember to ask your guests about any food allergies or dietary restrictions. You may need to make alternate arrangements for some guests.
The single most important piece of advice to remember, when planning a large meal, is that it's not the time to try new things. Choose dishes that are familiar and comfortable to you, things you cook with confidence in smaller quantities. That way you can focus on organizing your day and not have to worry about the cooking itself. Your local library should have several cookbooks with large-quantity recipes, and several websites, such as "Ellen's Kitchen," can also provide guidance or specific volume recipes.
Knowing how much of everything to purchase is also important. Make slightly more than you think you'll need. For example, if you're expecting 50, cook for 55 just to have some margin for error. Restaurants usually allow 1 cup of soup per portion, for example. Pasta dishes can be calculated at five portions per pound, and 1 cup of sauce per portion. With a roast, it's more complicated. Allow 6 to 8 oz. per person, but remember your roast will shrink by as much as 30 percent as it cooks. If your roast includes bones, the usable portion can shrink by 40 percent.
Cheat When You Can
Whenever possible, choose dishes that can be prepared ahead of time. Failing that, look for meal ideas that allow for ingredients to be prepared in advance and then assembled on the day. Leave as little as possible to be done on the day, and you'll be a long way ahead. Provide healthy finger foods, like vegetables and dip, in case things go more slowly than you'd anticipated. If you're on good terms with a local restaurant, they might be willing to heat the food for you at a reasonable price, eliminating another source of potential problems.