Olive oil is a common go-to for salad dressing but try branching out and using walnut oil, safflower oil, or sunflower oil to add another level of complexity to your greens. These oils work well in salads or cold dishes; however, they should not be used when cooking because they have a low smoke point.
An oil's smoke point refers to the temperature that will cause it to burn and smoke. It's important to cook with oils that have a high smoke point because this will guard your food from having a burnt flavor as well as destroying beneficial nutrients found in the oil.