Because vegetables cook more slowly than meats in the moist heat of the slow cooker, they should be cut or chopped in roughly the same size, and then placed in the bottom of the slow cooker. Meat can be browned before being cooked, though that step isn’t necessary.
Browning helps reduce the fat content in large cuts of meat, like roasts, and also caramelizes the sugars in the meat, thereby adding to its appearance and flavor. Ground meats are typically browned before cooking in the slow cooker – to reduce the fat content and to keep the integrity of the product intact (you shouldn’t have to brown ground meats if they are very lean). The meat will then melt into the recipe. Trim off any visible fat from cuts of meat, as the fat will make the dishes cook faster.