DS won't eat a lot of veg but he is the fruit monster. Here is a typical day:
Morning: gets up at the bloody crack of dawn and helps himself to oranges / apples / satsumas before breakfast
School: he refuses to take a mid morning snack and they rarely have fresh fruit in school
After school snack: I would normally have a bowl of fruit out - grapes or strawberries, blueberries, raspberries etc - I put out whatever as much as I am happy for them to have. He usually sneaks in another apple.
Evening meal: I always try to include something he loves - he hates carrots or peas but loves mini peppers, tomatoes in season, sweetcorn. Dessert is fruit that DH prepares as I can't be bothered with chopping and peeling - pineapple, watermelon, mango, pomegranate
He is not so keen on veg but loves things like lentils and beans and some nuts / dried fruits. I am okay with that so I offer whatever other veg we are having with meals but i don't push it. DD used to eat anything and everything but she is now a picky teenager who sneers at anything that isn't white toast <sigh>
I would advise approaching the whole thing as something positive - go to the supermarket with them, let them choose for themselves and try things, there will be something they enjoy.