There’s a flaming debate on which the best method of acquiring a language is. There are two main methods of learning a language: the natural and the artificial way.
The first at hand, and by far most popular method of learning a language, is the natural method. Some linguists support the natural method, which means getting in touch with the new language and omitting the mother tongue as much as possible while learning. Instead of using the known mother tongue, a teacher or language trainer can use sign language and drawings in order to explain new words and the meaning of different expressions in the new language. In this case, the teacher appeals to the intuitive skills of the learners who will learn the language by imitation.
Also, if a person is exposed to a multilingual environment, s/he can learn two or more languages using the natural method with no difficulty at all. Being exposed to a multilingual environment means being contact with two or more languages, be they spoken by parents/grandparents, or spoken on TV or at a foreign language kindergarten or school. Being a method based on imitation, this method is very effective for kids and young learners as they have a strong imitation instinct and an absorbent brain that records easily.
On the other hand, there are people who are not responsive to the natural method of learning a different language. Those people need to have grammar and phonetic guidance in order to understand how a language works. The linguists that hold up to this artificial method agree to the fact that the natural language is effective only to a certain point, and that one cannot possibly speak a naturally acquired language 100% accurately, as mistakes might slip in. As a result, some agree to the need for a grammar and a dictionary. However, knowing the grammar rules and a massive number of words will not necessarily mean that these will be used correctly, and one might encounter difficulties when it comes to expression. Consequently, one will need a great amount of practice.
All in all, the best method of learning a language is the one that works for you. You can try the natural way and after a while go and double check with a grammar book, or simply go for the theoretical part from the beginning.