Need a tips on dieting/ to get a healthy life?

I'm 18 years old,now waiting for my results,waiting for university offers that I believe will be out by early February. I am having a long holiday and I gained like 10 kg now I am 65 kg,I need to shed a lot well not technically a lot,at least I need to be at my ideal weight,I am afraid I might be having cholesterol/high blood pressure/diabetes because all those things run in my family,my dad he has cholesterol and he depends on med.Same goes to my aunts and uncles,my grandfather died because of diabetes. I need to start taking care of myself but I don't know how,what is the suitable exercise for me,how this how that. I don't want to be super skinny but I want to reduce the risk me of getting any of those.
Need a tips on dieting/ to get a healthy life?
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