What I've found work for me over the years...
On a workday having porridge for breakfast (topped with nuts & seeds) fills me up and keeps me going. If I have cereal or toast I tend to get so hungry in the evenings and just want to snack.
I weigh out portions of rice and pasta (2oz per adult) as otherwise I just pour and guess and over estimate and then over eat.
I eat breakfast, lunch & dinner and then in between only if I'm really hungry and after I've had a drink have a snack. I've found when I usually had a snack in the past I wasn't hungry I was either thirsty, bored, or just wanted a sweet treat but wasn't eating for hunger. (I used to snack A LOT)
I try to eat as little ultra-processed food as possible, though it is hard!
I have little to no self control with chocolate so I just don't have it in the cupboards, I know if I buy it I'll just eat 3 chocolate bars in a evening or an entire sharing bag in one go. Instead I buy myself a chocolate treat once a week and then have it over the weekend. Once it's gone it's gone vs bulk buying sweet treats and thinking I'll have 1 a day and never do.
I eat around 1,300-1,500 calories a day.
I do eat out, but only occasionally, but the portion sizes are always too big. I don't feel I have to eat it all though. Often stop eating the main even when I could eat more to squeeze in a dessert!