If you have a picky eater on your hands and I know I do here are some tips for trying to get the little fussy one to eat.
First of all don't serve them snacks too close to dinner or lunchtime. Your mother probably practiced this rule with you too and for a good reason. A kid with a full stomach is not going to feel like eating. A picky eater will have even less motivation to eat if his or her tummy is full. Do not overfeed your child and he or she will want to gobble up everything on his or her plate. This does not mean starving the kid. However creating a slight sense of appetite is not going to hurt things.
You should also limit the amount of juice and milk that you give your child during and in between meals. Both juice and milk fills them up so they do not feel hungry. Whatever you do not give this picky eater carbonated or sugary drinks as that can make them act very trance. Coke and Pepsi are extremely bad because they contain caffeine.
If your child is served a different type of food than the rest of the family then the child could be jealous. Serve the child up a bite of what you are eating which is a 'reward' bite if they finish the other stuff on their plate. However do not use sugary foods like dessert as a reward. This can cause the child toga in weight and create an unhealthy expectation for your child each time you all sit down together to eat.
If your child is not cooperative then try to stay calm. If you yell, berate or get upset at your child then both of you will be too stressed to focus on eating. You do not want your child to develop a negative attitude towards food. Kids that are yelled at while eating end up being too skinny or too fat as the result of eating disorders they develop. Many become binge eaters who stuff themselves when others aren't watching so they will not be watched or criticized like they were when they were toddlers at the dinner table.
Another good trick is to play with the shape of the food. Get some heart or animal shaped cookie cutters and make them into fun shapes. Another tact is to make up a story using the food. Lots of kids can be encouraged to eat their food if they are allowed to play with it first.
If your kids won't eat what you serve them or will only eat just one type of food then try putting some protein with it. My little boy ate nothing but bananas and tomato soup for years. He was okay but in order to add to his protein uptake I often added peanut butter to the sliced up banana that he would often have for breakfast, lunch and dinner. I simply could not get him to eat anything else.
Yet another neat trick is to let them eat with a stack of measuring spoons. Kids enjoy this for some reason.