The best way to do this is to talk to the child right when he is in the womb itself. This will not only create a bond between you and your child but also develop his language skills. You may not be able to test it but it is true just like we can't see air but can feel it. The results will be amazing and you will find that when your child starts attending school, you won't need to pluck your hairs off for teaching him how to learn ABC or 123. You can even make him listen to good music as children love good music and respond to it. But please don't put it very loudly as that can be injurious and also please do not put very rough music. The music should be soft type - hope you get the idea clear.
And for those parents who think they have missed an opportunity by not speaking to their little one in the womb; no need to worry. There is no better time than now to start. Your child is a separate individual, a combination of both you and your spouse. He will have the characteristics and abilities of both but it will have some uniqueness of his own too. So, let it develop and blossom and don't push for anything.
One word of caution: Don't be very pushy and start teaching your child each and everything you want or see in the hopes that your child will become an Einstein overnight. This is not a rat race that we are participating in. This exercise helps to bring out the mental potentials of a child to the fullest at an earlier stage rather than waiting for him to grow up and find it out himself. If you become too pushy and put your ambitions on the child at such a young age and push him to learn, the entire system will not only fail but backfire and this may hamper the overall development of your child apart from other complications. So, don't treat your child as a competition machine but treat him as a rose plant that you need to water everyday and wait for it to blossom. When the right season and time comes, definitely it will.
Good luck and happy parenting!