Is your child very aggressive? If he hasn't outgrown aggressive behaviour by the age of six, don't ignore it.
When a child shows aggressiveness, most parents tend to dismiss this as a factor of their age. "Oh, he will grow out of it," or "Boys will be boys" are common excuses for violent behaviour at a young age - and to an extent, these excuses hold true. Often children reach their peak of aggressiveness at around 4 years of age, and after around 4 or 5, they should start mellowing down.
First of all, understand that most children lose all traces of violent behaviour as they grow up, but if such behaviour persists, it is a cause of concern. Parents don't realise this, and continue thinking that their child's aggressiveness will go away on its own. If you don't start paying attention to your child's aggressive behaviour even after he crosses the age of 6, chances are such behaviour may continue into his teens and beyond, and could even lead to delinquent behaviour.
If you don't want your child to be the one sent home from school or expelled for assaulting a classmate, or put behind bars for pulling a knife on someone, get working on his aggressiveness early on, and channel it in the right direction.
Identify the cause for your child's anger and aggression. The family situation has a lot to do with your child's ability to handle his emotions.
Fights at home
Do you fight a lot with your spouse in front of your children? In doing so, you are harming your child's psychological well being far more than you realise. Also, what may seem like harmless spats to you will not seem the same to your child - and while you emerge from such arguments unscathed, your child will not. It may be hard, but work with your spouse to avoid creating a scene in front of your child.
More serious fights will naturally have more severe ramifications. Warring couples often live together for the sake of their children, but what they may not realise is that their constant fighting will cause more damage than a clean separation will. Children will be happy when their parents are happy.
As soon as you notice traces of anti-social behaviour in your child, don't ignore it. Doing so will only reinforce your child's belief that such behaviour is normal. Encourage your child to mix with others his age. Invite his friends over, and get him enrolled in activities that involve mixing with others, like tennis lessons.
If you live in a neighbourhood where your child is exposed to violent behaviour, it will certainly have an effect on his character, and even excellent parenting may not be able to compensate for harmful peer influence. If you cannot afford to move out of a rough neighbourhood, your next best bet would be to keep your child away from the neighbourhood crowd, and do your best to be particular about who he hangs out with.
Your best bet would be to shower your child with love, and let him know that you will be always there for him.