Also telling a potential employer that you "can make [his] company operate more smoothly" sounds a little presumptuous.
What you need to do is 1) decide what personal qualities are needed for the job, 2) decide whether you have any of them, 3) tell you potential employer about the ones you have and why you think they would be relevant.
>Can I say "my skills will contribute to your company's success"?
No, they want to know how? Why do you think this?
They want some evidence that you've thought about the specific job and questioned your ability to do it.
Student or Learner