Limits should be about free time activities to what video game they can play. To many parents allows children to play violent because all other children at school does it, or your child might play those games anyhow. By setting limits as in what they can do:
* Letting your child have candy only on Friday´s.
* Watching tv after doing their homework.
and so on..
Limits what not to do :
* Play violent games.
* To not eat candy on normal school days.
I quote from an news article:
* Give modest, honest praise for good behavior, which will encourage more of it. Don't praise excessively or outlandishly
* Insist that the children work or play alone each day. This will instill self-confidence and a sense that learning is enjoyable.
* Speak positively about children when they can hear you.
* Don't treat children as little adults. Give them limited, child-level choices. For instance, if you expect them to do something, don't ask them if they'd "like to" do it. Simply tell them positively and firmly of the plan.