Niceness is overrated.

But seriously, you seem plenty nice in my opinion. And that's just it really. "Being nice" is a matter of opinion. And there is fine line between niceness and some not-quite-nice terms (sucking up, brown-nosing, etc.).

How can one be nicer? Well, there's always practicing the Golden Rule. Treat people how you would want to be treated. Then there's smiling. People generally think people who are smiling are nice. Helping others, even if it is just something small.

Maybe I don't know what it is you are really asking. The things you described in your post make you a nice person in my book. You would think I would know all about niceness with my current title, but I don't really do anything that out of the ordinary. I don't think there is a set equation to achieving niceness.