R-E-S-P-E-C-T. Can't you get just a little bit? Young children can be such rude little creatures, demanding the things they want, pushing you out of the way and just generally disobeying everything you say. You know that those types of behaviors aren't going to get him far in life. He needs to be respectful of you and others. Teaching respect can be a long process, but the rewards of a well-behaved child are worth it.
Model respectful behavior. Kids are great little imitators, and this seems to be doubly true when they're mimicking bad behavior. If you treat your child without respect -- yelling at him because he's not adhering to your schedule or refusing to allow him to select his own clothes -- then he's going to treat you the same way. Respect is about the relationship that you have. It needs to go both ways.
Spend time with your child. Actively engage with him every day. This time shows him that you love and respect him and deepens your bond, which will translate to respect from him.
Read children's books about respecting others. Beyond simple modeling, children sometimes need to see examples of what respect and disrespect look like in a way that's not as connected to their own realities. Check out "The Berenstain Bears Show Some Respect" or "Dude, That's Rude!" from the library and read it with your child. Ask your child questions about what he's read. You'll probably find that he recognizes the bad behavior and wants to be the child that does good.
Praise him when he shows respect. Children thrive on positive reinforcement and need to know they're doing a good job. A well-timed "Wow, you used really polite language!" or "It makes me feel happy when you listen to my words" can make a big difference.
Ignore your child when he's being disrespectful. So your child screams out "Mom! Gimme a drink!" from the next room? If you do it, he'll never change his ways. Either ignore him until he uses the proper language or remind him, "I only respond to respectful language," and he'll quickly get the point.
Develop a disciplinary plan that works for your child. Though many of the previous suggestions will work if you keep them up, there may be times when you have to take disciplinary action. Every child is different and responds to different things. You might discipline him by taking away privileges like watching TV or you may decide that he needs to sit in a "time out" chair for a little while. After the punishment, discuss why you were upset and how he can act more appropriately next time.