“I think I’m improving little by little.”
You've been playing racquetball with a friend every week. When you started, you weren't very good. Now you just scored a point against your friend & he compliments you. You say this.
I think I’m improving little by little.
Use the phrase "little by little" to describe something that happens slowly. Another way to say this is "gradually", but "gradually" is more formal. "Little by little" can be used for both positive and negative things:
We're starting to get the hang of it little by little.
She's losing her memory little by little. Soon we're going to have to move her into a nursing home.
There are actually a lot of phrases like this that express doing something slowly and steadily. Here are a few:
bit by bit
inch by inch
day by day
one by one