We have the concept of “Separate” because, despite your best efforts at keeping your hands, utensils and surfaces clean, cross-contamination can still occur. You need to keep uncooked meats, fish, poultry and eggs away from other foods, whether the other foods are raw or already prepared. You also need to make sure raw meats, fish, poultry and eggs touch only the surfaces on which they are being prepared.
In the market, keep these foods away from other foods by keeping them in a separate section of your shopping cart. Keep them separate at the checkout, and ask the bagger to bag them on their own.
In the refrigerator, keep these foods in sealed plastic bags so their juices will not drip on and possibly contaminate other foods (and surfaces). As much as possible, keep meats, eggs, fish and poultry in separate refrigerator compartments. Keep eggs in their original carton and avoid using a built-in egg tray, if you have one. To promote their keeping power and discourage bacteria, keep eggs in the main part of your refrigerator; it is colder than the door.
In the kitchen, use one cutting board for poultry, fish, and meats, and another for non-meat produce like vegetables. A good system is to use cutting boards of different colors, so you can keep track of which is which. Thoroughly wash all cutting boards after each use. Replace cutting boards often as they wear out. It pays also to stretch the “keep them separate” concept to knives and handling utensils like spatulas.