Quantity is all about shopping -- how much should I get? How many portions should I be eating? Am I going to overshop or undershop?

To help sort out these questions and more, chef Ryan Scott is offering tips for three of Thanksgiving's most commonly used foods.

1.) Turkey

With the smaller birds, Ryan says you want to have two pounds per-person. That may sound like a lot, but it will come in handy when you're making leftovers over the long holiday weekend.

If you do a bigger bird, Ryan says one and a half pounds per-person is perfect.

2.) Potatoes

Ryan recommends going with a one potato per-person rule. If you want leftovers, however, both Rachael and chef Emeril Lagasse recommend going with one and a half potatoes per-person, especially if you want to make sandwiches the next day.

3.) Dessert

When you're making or buying pie, Ryan says you shouldn't go crazy. Keep it simple by choosing one or two -- perhaps an apple and a pumpkin. When you're serving, allow one (yes, one) slice per-person.

For more Thanksgiving tips and recipes, head to RachaelRayShow.com.