The first step to deciding what to do, is to take a long hard look at what you’re really doing.
That means understanding your exact behaviours:
What do you eat?
How often?
Do you snack?
Drinks?
Alcohol?
There are a number ways of doing this.
One is to keep a food diary. Just record what you eat every day. On paper, on your phone, on your computer, in a notebook. Wherever you like. Counting the calories can be tedious, but can also be very useful. But even just by recording all the food and drink you consume, it will give you a pretty good idea of what needs changing.
Another is to look at what you do. What are your behaviours in terms of food and drink. For example, I put a lot of butter on my bread. I like butter and I like bread. Some people drink wine and beer in the evening. Record your behaviours to see exactly what you do.
Next plan what you could do.