For us, the idea that ;if you never had it you dont know what you're missing' has worked so far.
For example, from when he first started eating bread, he got whole grain, crust on bread. He has never had white bread, so he is used to the whole grain and eats it! Same with pasta.
Also he has always been offered mostly veggies on his plate, so thats the norm, you eat lots of veggies. Desert is usually fruit based, except for rare occasions where my dad bakes brownies or someone has a b-day and we have cake.
He has a shelf in the pantry that he can reach that has healthy snacks divided out for him - nuts, fruit, dried fruit, healthy cereal, ocassionally one of his special granola bars (he is allergic to oats). In the fridge we always have leftovers from dinner, cooked and raw veggies ready to eat, vegan cheese, tofu chunks etc.... so if he ever says he is hungry, he gets one of those things vs. a cookie or something.
'Junk' food is a special treat only, always has been, and so he doesnt expect to eat that kind of food every day (and besides, he has allergies and is vegetaian, so that resticts the options for 'junk' right there!).
Another thing is that we have always given him a big variety of food choices. I NEVER would not offer him something because 'it might be too spicy/sour/spiced/or whatever' or beacuase 'its not kid food'. He always just got some of whatever I was going to eat, not something made special for him.
If he ate it, great, if not, he could just eat the side dishes (we always have some sort of veggie as a side). Same thing at restaurants, the kids hoices are ALWAYS unhealthy, so I just share my meal or get him some sides of veggies depending on what he prefers.
And just beacuse I dont like something, doesnt mean I dont let him taste it!
He actually likes food that is more spicy than I like to eat, and some veggies that I hate eating (like bananas, mushrooms, peas and green beans).
I think if they are given healthy stuff from right when they start eating, then thats what they expect food to be. If they have acess to junk any time they want it, then they will be more likley to eat it/get into bad habbits.
What I dont get is the people who give their 6month old soda in a bottle and feed them hot dogs and chicken fingers and then wonder why their kids donteat right...