There are a lot of ideas floating around on what you need to do to become a master Japanese. Daily practice, immersion, memorizing the dictionary, getting a boy/girlfriend who is a native speaker ... the list goes on and on.
But, for me, the most important thing for you to do is to embrace being wrong.
This sounds awful, right? No one likes to be wrong! It's embarrassing, it's humiliating, it hurts your ego. And yet, when it comes to languages, it's the most important thing for you to do.
Speaking a new language is all about being wrong. You're going to stumble and say the wrong thing sometimes, but if you take one instance of being wrong and run and hide, never willing to try again, then you will never improve. Listen to any small children talk. They use improper grammar and mispronounce words, but do they ever care? No way! And this is how you need to act. Mistakes happen, but they're fabulous learning experiences.
Once I accidentally said kusokuso instead of shikushiku when telling a story to a Japanese friend.
Shikushiku is the onomateopia for crying.
Kuso is... well, a stronger word for "poopoo."
Yes, she laughed and, yes, I felt embarrassed, but I didn't let that stop me from talking with her. I didn't let my fear of making a mistake overtake me and it helped me continue to improve.
Which is what you should do with your learning. Don't hide when a teacher asks a question because you're afraid of giving the wrong answer. Being corrected is BETTER than being right all the time because it gets pounded into your head so much harder! Rather than shy from an opportunity to practice with someone because "I'm not ready yet, I can barely hold a conversation in class" you need to just dive in and give it a go. You're going to make mistakes along the way, but being wrong and learning from it is a million times better than never trying.
Afterall, I never did mix up those two words again. ;)