It almost seems like kids are born with bad table manners. As soon as they come into the world, they start spitting up and burping! A few months later, they start eating with their hands, and they're certainly not neat about it. But it won't always be this way. You can start enforcing table manners with your toddler so she's ready to dine in the finest five-star restaurants when she's older.
Eat together as a family and model good table manners. You can't expect your child to have proper table manners if she never gets to see them in action or if you are slouched in your chair, eating with your hands. Of course, you can have a pizza night every now and then, but don't put the jug of milk on the table and let everyone slurp out of it. Enforce proper table manners for yourself and your partner, not just your child.
Include your child in preparing for a meal. Even toddlers and preschoolers can learn to set the table with a little help. They can put the salt and pepper on the table, give everyone a napkin and lay out the cutlery. As your child gets older, you can continue to add to her knowledge of table etiquette, until she is ready to eat with royalty.
Start early. Table manners are more than just saying "please pass the potatoes." It starts from the time you call your kids for dinner. First they should wash their hands and faces, then come to the dining room or kitchen and find their spot at the table. Toddlers should be encouraged to sit on their bum for the whole meal -- no escaping until everyone is done. Then they can say, "May I please be excused?" and take their dishes to the kitchen. If they can't handle their dishes yet, just give them a cup or spoon so they learn the action.
Be consistent. Don't aim for one family dinner a week. Aim for at least one family meal a day. Eat the evening meal together on school days, but on the weekends, try to enjoy breakfast and lunch as a family as well. For fun, include one "fine dining" night a week, where you can introduce classical music and white linens to your kitchen. Just be prepared to spot-remove stains on your fabric!
Praise your child. Find specific positive points and tell her what a good job she's doing. "I like how you are sitting up straight -- good job!" Find several things at each meal to praise her for, so she knows she's on the right track.