Students learn from actions. It is important that parents not only talk about the moral values they want their children to inherit, but also model them on a daily basis. In my opinion, consistency is very important for kids when it comes to their learning moral values - if there are television shows, video games, songs etc. which show values which are different than the ones you are trying to instill, then those are probably not media your child should be watching/using.
It is also important that the people your children are spending their time with model values which are consistent with yours. Obviously, it is not possible for your child to never encounter someone with different moral values than your own (and that's probably a good thing!) But if someone is taking care of or around your child on a regular basis, then I believe it is important for that person's values and yours to be in general accordance. I also think its important to discuss moral values with children from the time they are young, they are more likely to take on those values themselves as they grow if it is something they understand and believe than if it feels as though it were forced upon them.