I took a deep breath and tried to calm down a bit.

He took a deep breath to try to calm down.

He took a deep breath in an attempt to calm down.

I endeavor every day to improve my Japanese.

He seems a little tired.

He is learning Japanese little by little.

If you try a little harder, you can achieve your goal.

He didn't listen to my story at all.

He can speak a little Japanese.

I will try to finish my work as quickly as possible.