1. Eat about the same amount of calories every day and make sure you get enough protein and nutrients.
2. Weigh yourself every morning right after peeing and before eating/drinking anything
3. Average your weekly weights and adjust calories as needed. Dont pay attention to daily weight fluctuations.
Meal prepping and eating roughly the same things every day makes things easier because you get less water weight fluctuation and its easier to track, but you don't have to as long as you are tracking perfectly. For losing weight, maybe 1-3 pounds of actual mass per week is practical depending on how hard you restrict. When you first start, you might get larger differences due to water weight changes, especially if you switch your diet