Be consistent. One of the major problems with dog owners is that they start out with great expectations, only to become frustrated and give up. Remember that you are the owner and, therefore, responsible for your dog and teaching it proper behavior.
Develop a training plan. Just as you didn't learn to recognize English words in six months, neither will your dog. Figure out a reasonable English development plan -- say responding to one command word a week -- and build in frequent reviews.
Establish a reward system for your dog learning a new command. Pat your dog or give her a small treat when she demonstrates that she has learned a new English word by exhibiting the appropriate behavior.
Identify the English words you want your dog to understand. Write them down and tick them off as your pet adds them to her vocabulary. Make them monosyllabic to begin with ("sit") and then work up to short phrases ("lie down").
Use an association strategy. The reason most dogs learn the English word "sit" is because owners gently push their pets into a sitting position. Work out an association for other English words you want to teach your dog to make it easier for him to develop an English vocabulary.