First of all, allow me to be clear about one very key point in learning Japanese...
LEARNING SOLELY FROM ANIME/MANGA/DORAMA/J-MUSIC=NO
What you learn from there is either incredibly archaic, or way overblown and will make you look strange when used in a casual conversation. Imagine if someone you knew spoke like they were in a cartoon or a soap opera every time they spoke. If entertainment media is all you learn from, that's what you're gonna sound like; not very inviting of conversation, if you ask me. Remember, lessons are the base, and media supports and reinforces what you're learning, never the other way 'round.
Moving on, though, like any other student of any other subject, you must be willing to learn from both the lessons offered and the stumbles you'll encounter; because if there's one thing you'll do a lot of it's stumbling. (for a while your Japanese may sound like this, and that's ok. There are no mistakes, only variation, as the Zen saying goes.)