Sneaky ways to add vegetables to your diet
Mealtime Problems and Tips for Dealing with Picky Eaters
Don't get emotional and don't ever use food as a weapon.
Stop worrying! Your child will not starve -- at some point he will become hungry and eat. Don't be tempted to give your child junk food, which he will want to eat, simply to get something into him. This lays the ground for all sorts of blackmailing in the future, using food as a weapon.
Never use food as a bribe or a reward. Let food be what it is - a source of nourishment and enjoyment.
Also, keep in mind that different children have different appetites, just as adults do. A lot of children eat more just before a growth spurt, when they fatten up, and are often less hungry when actually going through the growth spurt. Don't let these times become the basis of abad emotional relationship with food and meal times.
Teach kids to love vegetables early.
Introduce your child early to different vegetables so that they grow accustomed to the different tastes. Always try to keep fruits and vegetables in the fridge, washed, cut and ready to eat. Personally, my daughter grew into a phase where she wouldn't eat any vegetables except tomatoes until I started cleaning and leaving open in the fridge carrots, celery and cucumber slices. I was amazed to see her open the fridge and grab some.
Remember that calories, not protein, are the main issue with young children.
Be the good example. Eat well and keep good food around.
It's harder to get kids to eat healthy foods if there's tons of junk food lying around the house. You can't blame them for begging and whining if they see junk food around, and certainly can't blame them for wanting it if they see you eating it all the time.
Personally, I find that if I make a salad for myself right before lunchtime my kids will pick at it and eat vegetables that way, whereas they wouldn't ever eat something like lettuce if I gave it to them with their lunch. So try taking out a salad, or veggies and dip for yourself and see what happens.
Eat a big healthy breakfast. My daughter is big on breakfast, and I find that when she eats a bit breakfast, I don't have to worry as much if she's not very hungry at dinner.
Eat together. Don't watch television or work and let your children eat dinner without you. Remember that even babies like being talked to, even if they can't answer back. It might feel a little silly to have nonesensical conversations but it will make their mealtimes enjoyable and will encourage healthy habits for everyone.
About bad foods:
It's best not to make a big deal out of "bad" foods. It wont hurt them to touch junk food every once in a while, and by letting them eat special foods at parties, etc, they'll learn that some foods are okay to eat sporadically. Plus, I, personally, wouldn't want to risk them eating only junk foods as a way to rebel when they become teenagers/adults. 
Help kids connect with what's going into their
mouths.
Let kids grown their own food. They'll be fascinated by the process of seeds turning into plants. Even if you only have a flowerpot on the kitchen window sill, it's easy to grow vegetables such as sprouts, parsley and even tiny tomatoes.
Hide and Seek : Tricks for Disguising Vegetables
Often I find the best way to add extra vegetables into a meal is to sneak it in there when no one's looking.
The Sneaky Mashed Potatoes: If your child likes mashed potatoes, you can add a healthy of variety of other vegetables in there and they wont know the difference. The best examples are cauliflower and parsnips. Other good examples are sweet potatoes, yams, broccoli, mushrooms.
Sneaky Tomato Sauce: If your child likes tomato sauce you can also sneak in vegetables like mushrooms, very finely chopped broccoli and cauliflower, and also roasted red papper. In fact, you can make roasted red pepper sauce instead of tomato sauce one night and they probably wont be able to tell the difference. Just cook the vegetables, blend them with a food processor or blender, and mix them into the tomato sauce.
Disclaimer: The information on this site was gathered from different sources including How it All Vegan and What Should I Feed My Baby. I highly recommend purchasing these books. I am not a registered psychologist, nutritionist or professional of any kind, so please, if you are having serious problems with your child's eating habits please consult a doctor.