Just like how you check the weather forecast before heading out, you need to monitor the temperature of your turkey while it's cooking. You want to make sure the internal temperature reaches a safe minimum of 165°F (74°C) to avoid any, ahem, fowl play. Use a meat thermometer to check the temperature in the thickest part of the breast and the innermost part of the thigh.
Cooking a stuffed turkey is like solving a puzzle - you need to make sure all the pieces fit together just right. The stuffing can be a bit tricky, as it needs to be cooked to a safe temperature as well. Make sure the stuffing is loosely filled in the turkey cavity, and that it's not packed too tightly, or it might not cook evenly.