Check the game out before you let your children play it. Make sure it is appropriate for their age by reading reviews and other details about the game online. Sometimes the rating isn't enough and it is best to check out what others have to say about the game and the contents of it.
Sell your used games to buy new or new to you games. Video games are not cheap and some of them you have no use for after you beat. Do your research and find stores that buy used games. These stores will either pay you in cash or in store credit. This allows you to get games you want without spending a lot of money.