When I start learning a language, what should be my focus?

Define your reason for learning a language. Your reason for learning, your motivation, is very important in figuring out what should be your area of focus. If you are learning a language in order to travel to a foreign country, then there may be little need for you to bog yourself down trying to learn all the grammatical rules of the language. On the other hand, if you are studying for a written language exam for a college course, then you will need all the grammatical rules and then some. If you are learning a language for work purposes, then you probably want to focus first on learning to speak and understand the language, as well as the culture, since you will be dealing with many native speakers.