We don't make him try it and have no rules about food. DH and I are both very very sensitive and picky eaters and grew up being forced by our parents and society/friends and really really resented it - still do! It wasn't the one bite rule like Anna has though. Ours was sat at the table until the food was gone

or whatever.
He's a great eater when he's hungry so when he won't try something we know a) he's not hungry or b) he just doesn't like the look/smell of it, in which case fine. We still continue to offer the said food though. He's not getting off that easily lol He'll see it on his plate again and again and one day we're pretty sure he'll try it. We also don't provide alternative meals. If he rejects the dinner that's made, that's it. He gets his fruit like always and some milk before bed and he has to make do with that.