Great question. What I do is the following 1) Most languages only really use 30-40 verbs for the majority of what you talk about 2) Of these the core 20 verbs will be special (irregular) 3) You only need about 5 tenses ( I guess, present, a couple of past, conditional and a future) 4) English has no gender so that is easy 5) not that many pronouns 6) build sentences. So, I go to the airport in my car, i went to the airport in your car, he will go to the airport in his car, she could go to the airport in their car, I used to go to the airport in our car. If you are happy with that then you have the core, well done. Now expand the subject matter with your sentences and do this in the area of your favorite subject. So it you like cooking, make up the sentences about cooking.

Practice makes perfect! The more you speak, the more you listen, the more you train your ears to hear little nuances, the better you become. And don't worry too much about making grammar mistakes. It's part of your charm!

You need a well organised grammar course and a lot of practice.