"If a recipe calls for a nonstick skillet, what do I have to change in order to make it work in a regular stainless skillet?"
Often the main difference would be the amount of oil or butter you need in the pan to prevent food from sticking. While not a hard and fast rule, a good guideline to use is that it takes about 1 tablespoon of fat over the surface of a 12-inch skillet to keep food from sticking.
If your recipe already calls for about oil or butter in the pan, you may not have to make any changes to ingredients. Do watch your cooking times though, and pay attention to visual cues over time in the recipe. If you are supposed to cook something for 5 minutes, or until lightly golden—use the color, not time, as your guideline.