Today's tip may sound like a no brainer, but I know first hand that some people (my husband) needs this reminder. Case and point: My husband thinks that he only needs to say "but it's good for you" and whoever he is saying it to will magically like the food he is mentioning. That may work for my husband (with the exception of peas) but I don't know if it works for anyone else I know.
So find out what fruits and veggies your child likes, and serve them that. I do occasionally try to reintroduce something my children haven't liked in the past because it can change, but my middle schooler doesn't like nuts, my high schooler likes a big honkin' salad (pictured above), my daughter in elementary doesn't like yogurt with chunks of fruit- so all of these things are considered while making their lunch. And that makes for happier children and a happier mom, because wasting food frustrates me more than slight pickiness.