I reccomend movies, youtube, books, etc and common media.
Another good way is by looking at dictionaries or forums if you'd like to know the way most people speak on the internet.
Talk to people who speak the language ! It's much easier to have them correct you during speech :)
And study the sentence structures + placement of verbs, adjectives and nouns ! I reccomend looking into person/place/thing and who/what/where/when/why if you'd like the upmost basics.