The only way to learn new language is just speaking. Grammar is nice but for teachers who wanna improve they skills and unfortunately useless for beginners. Writing or grammar will come naturally with time.
Good idea is also start learning with writing down words which sounds or spell the same as Polish words or some funny meanings in Polish language.
The most important is practicing it as often as possible. At the beginning good idea is start watching well known films in original language. E.g. if you wanna learn British English watch Monty Python's Flying Circus and if you wanna learn American English watch Married with Children.
And last think, courses or schools aren't enough for learning language and it's always better to have some fun.
The best way to learn English
The best way to learn English is to speaking, speaking and again speaking idealistic with nativ. I practice my English with tutors from UK and the USA via Skype on preply.com/pl/.
Watching movies will help you
Watching movies will help you to understand the melody of a language, but will not be of much help if you do not know a single word. In my opinion, the best way is to start with learning 1000 of the most popular words, which is enough to give sb basic knowledge and a solid base for future learning.
English
I think the best way to start learning the language is watching a movie or listening to music in this language. In the fast way know the words and we can lodge simple sentences .Another of the simplest ways of learning a language is learning with friends because we can supplement our knowledge and correct mistake.Of course, to get the best results we have to learn as much as we can . The more words we repeat the more words we will remember . I think memorizing words is the most important because thanks to them we create a sentence.Last but not the worst way is to learn in school , but I think in school we are not able to learn the language well because our teachers spend too little time to study us.