Hey, I thing that the best way it´s talking and listening, because when we were children we didn´t learn the rules of grammar, we started to learn our first language hearing and talking and after this we studied the grammar in the school. When we learn the grammar everything seems to be easy, but when we try speak something it´s terrible, because we realize that only the grammar can´t help us. So the only way it´s trying to speak, to think in portuguese, to listen this language all the time, to read texts, etc. If you want I can help you.