My best tip is to eat a really big salad with a lot of crunchy green stuff, a pile of protein and some low-fat dressing you don’t hate. It looks huge and fills you up. Chuck some tomatoes and other things in there. A hard-boiled egg, for example.
Most of the time, I just attempt to eat less sugar. That seems to do the job. Low sugar, high-fibre cereal with semi-skimmed milk is good. Some dried fruit makes it nicer.