My biggest tip for tracking diet is to use some form of app/program to count calories. I know it sounds tedious but there are so many easy apps nowadays. I personally use Myfitnesspal; for example i eat a banana, i literally type "banana" and it automatically gives me the calories with fat, carbs, protein percentages. It calculates calory intake based on your height, weight, gender, activity level etc.
Edit: it also gives u a choice how much per week you want to lose; When i have high stress periods i go with 0,25kg/week and then when i have more time and can work out more too i got up to 1kg/week and it calculates everything for u